Sensors for catheter pumps

ABSTRACT

Sensors for catheter pumps are disclosed herein. The catheter pump can include a catheter assembly comprising a catheter and a cannula coupled to a distal portion of the catheter. The cannula can have a proximal port for permitting the flow of blood therethrough. The catheter assembly can include a sensor to be disposed near the proximal port. A processing unit can be programmed to process a signal detected by the sensor. The processing unit can comprise a computer-readable set of rules to evaluate the signal to determine a position of the cannula relative to an aortic valve of a patient.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 61/979,920, filed on Apr. 15, 2014, the entire contents of which areincorporated by reference herein in their entirety and for all purposes.

BACKGROUND OF THE INVENTION

Field of the Invention

This application is directed to a catheter pump for mechanicalcirculatory support of a heart, and related components, systems andmethods. In particular, this application is directed to sensors used incatheter pumps.

Description of the Related Art

Heart disease is a major health problem that has high mortality rate.Physicians increasingly use mechanical circulatory support systems fortreating heart failure. The treatment of acute heart failure requires adevice that can provide support to the patient quickly. Physiciansdesire treatment options that can be deployed quickly andminimally-invasively.

Intra-aortic balloon pumps (IABP) are currently the most common type ofcirculatory support devices for treating acute heart failure. IABPs arecommonly used to treat heart failure, such as to stabilize a patientafter cardiogenic shock, during treatment of acute myocardial infarction(MI) or decompensated heart failure, or to support a patient during highrisk percutaneous coronary intervention (PCI). Circulatory supportsystems may be used alone or with pharmacological treatment.

In a conventional approach, an IABP is positioned in the aorta andactuated in a counterpulsation fashion to provide partial support to thecirculatory system. More recently minimally-invasive rotary blood pumphave been developed in an attempt to increase the level of potentialsupport (i.e. higher flow). Rotary pumps have become more commonrecently for treating heart failure. A rotary blood pump is typicallyinserted into the body and connected to the cardiovascular system, forexample, to the left ventricle and the ascending aorta to assist thepumping function of the heart. Other known applications include pumpingvenous blood from the right ventricle to the pulmonary artery forsupport of the right side of the heart. An aim of acute circulatorysupport devices is to reduce the load on the heart muscle for a periodof time, to stabilize the patient prior to heart transplant or forcontinuing support. Rotary blood pumps generally utilize an electricmotor which drives an impeller pump at relatively high speeds. In thecase where the pump is remote from the motor, for example where theimpeller is in the body and the motor is outside the body, there is aneed for a robust and reliable connection between the motor and theimpeller. There may also be the need for forming a flexible connectionbetween the motor shaft and the impeller to allow free movement ofvarious pump components during use and when pushing through thevasculature to the treatment location. There is also the continuing needto provide these system components in a compact, efficient form factorto allow for percutaneous approaches.

There is a need for improved mechanical circulatory support devices fortreating acute heart failure. Fixed cross-section ventricular assistdevices designed to provide partial or near full heart flow rate areeither too large to be advanced percutaneously (e.g., through thefemoral artery without a cutdown) or provide insufficient flow.

SUMMARY

An aspect of at least one of the embodiments disclosed herein is therealization that the connection of a flexible proximal body to a morerigid distal segment of a catheter assembly can be better secured withan robust mechanical interface between one or more features of thesecomponents. For example, a distal end of the flexible proximal body canbe fitted with a device or structure providing an interface thatmechanically engages the flexible proximal body and that can be directlyjoined, e.g. welded, to a structure to which a load is applied.

In one embodiment, a catheter assembly is disclosed. The catheterassembly can include a catheter and a cannula coupled to a distalportion of the catheter. The cannula can have a proximal port forpermitting the flow of blood therethrough. The catheter assembly caninclude a sensor to be disposed near the proximal port. A processingunit can be programmed to process a signal detected by the sensor, theprocessing unit comprising a computer-readable set of rules to evaluatethe signal to determine a position of the cannula relative to a cardiacvalve of a patient during a treatment procedure.

In another embodiment, a catheter assembly is disclosed. The catheterassembly can include a catheter and a cannula coupled to a distalportion of the catheter. The cannula can have a proximal port and adistal port for permitting the flow of blood therethrough. The catheterassembly can include a sensor assembly. The sensor assembly can compriseat least one of: (a) a proximal sensor coupled with the catheter bodyand having a distal portion near the proximal port, and (b) a distalsensor coupled with the cannula and having a distal portion near thedistal port.

In another embodiment, a method of pumping blood through a patient isdisclosed. The method can include inserting a catheter pump into thepatient, the catheter pump comprising a catheter body, a cannula coupledwith the catheter body, an impeller within the cannula, a sensorassembly near the impeller, and a sheath disposed about the catheterbody. The method can include providing relative motion between thesheath and the sensor assembly to expose the sensor assembly to theblood. The method can include rotating the impeller. The method caninclude measuring a pressure of the blood with the sensor assembly. Insome embodiments, providing relative motion can comprise sliding thesheath proximally relative to the cannula and the sensor assembly. Insome embodiments, the cannula and impeller expand to deployedconfigurations upon sliding the sheath proximally. In some embodiments,the sensor assembly is disposed proximal the impeller, the methodcomprising sliding the sheath until a sensor element is exposed througha window of the catheter pump. In some embodiments, the sensor assemblyis disposed on a wall of the cannula, the method comprising sliding thesheath until a sensor element is exposed to the blood. In someembodiments, the sensor assembly is disposed in a central lumen of thecatheter pump that extends distal the impeller, the method comprisingsliding the sheath until a sensor element is exposed through an openingor window in the central lumen.

In yet another embodiment, a computer-implemented method for determininga position of a cannula relative to an anatomy of a patient isdisclosed. The method can comprise receiving a signal from a sensordisposed near a proximal port of the cannula. The method can alsoinclude processing the signal to determine a fluid signature related toa property of the fluid flowing through the proximal port. The methodcan comprise comparing the determined fluid signature with a baselinesignature, the baseline signature associated with a proper position ofthe cannula during a treatment procedure. The method can includedetermining the position of the cannula based at least in part on thecomparison of the determined fluid signature with the baselinesignature.

In another embodiment, a non-transitory computer-readable medium havinginstructions stored thereon is disclosed. The instructions, whenexecuted by a processor, perform a method comprising receiving a signalfrom a sensor disposed near a proximal port of the cannula. The methodcan include processing the signal to determine a fluid signature relatedto a property of the fluid flowing through the proximal port. The methodcan also comprise comparing the determined fluid signature with abaseline signature, the baseline signature associated with a properposition of the cannula during a treatment procedure. The method caninclude determining the position of the cannula based at least in parton the comparison of the determined fluid signature with the baselinesignature.

In yet another embodiment, a method of manufacturing a catheter assemblyis disclosed. The method can include coupling a sensor assembly to acannula disposed about an impeller, the cannula coupled to a distalportion of the catheter assembly. The sensor assembly can be configuredto measure a property of blood flowing through the cannula.

In another embodiment, a method of pumping blood through a patient isdisclosed. The method can include advancing an impeller assembly througha vascular system of the patient to a left ventricle of the patient. Theimpeller assembly can comprise an impeller and a sensor near one or moreinlets of the impeller assembly. The sensor can be configured to measurea pressure of blood flowing through the inlet(s). The method can includeactivating the impeller to pump blood through an aorta of the patient ata flow rate of at least about 2 liters per minute (Lpm). The method canfurther comprise maintaining an average pressure of less than about 15mmHg in the left ventricle of the patient.

In another embodiment, a catheter pump is disclosed. The catheter pumpcan include an impeller assembly comprising an impeller and a sensornear one or more inlets of the impeller assembly. The sensor can beconfigured to measure a pressure of blood flowing through the inlet(s).The impeller assembly an be configured such that the inlet(s) arepositioned in a left ventricle of the patient during a treatmentprocedure. The impeller assembly can be configured to pump blood throughan aorta of the patient at a flow rate of at least about 2 liters perminute (Lpm) and to maintain a pressure of less than about 15 mmHg inthe left ventricle of the patient.

In another embodiment, a method of pumping blood through a patient isdisclosed. The method can include advancing an impeller assembly througha vascular system of the patient to a left ventricle of the patient, theimpeller assembly comprising an impeller and a sensor near one or moreinlets of the impeller assembly, the sensor configured to measure apressure of blood flowing through the inlet(s). The method can includeactivating the impeller to pump blood through an aorta of the patient ata flow rate of at least about 2 liters per minute (Lpm). The method caninclude maintaining an average pressure in the left ventricle of thepatient of less than about 135% of the normal human average ventricularpressure.

In one embodiment, a catheter pump assembly is provided that includes anelongate polymeric catheter body, a cannula, and a tubular interface.The elongate polymeric catheter body has a proximal end and a distalend. The cannula has an expandable portion disposed distally of theelongate polymeric catheter body. The cannula can also have anothertubular portion that is proximal to the distal portion. The tubularinterface has an outer surface configured to be joined to the tubularportion of the cannula and an inner surface. The inner surface isdisposed over the distal end of the elongate polymeric catheter body.The tubular interface has a plurality of transverse channels extendingoutward from the inner surface of the tubular interface. An outersurface of the elongate polymeric catheter body projects into thetransverse channels to mechanically integrate the elongate polymericcatheter body with the tubular interface.

In another embodiment, a catheter pump assembly is provided thatincludes an elongate polymeric catheter body, a tubular member, and amechanical interface. The elongate polymeric catheter body has aproximal end and a distal end. At least a portion of the tubular memberis disposed distally of the elongate polymeric catheter body. Themechanical interface is disposed between a portion of the elongatepolymeric catheter body and the tubular member. The mechanical interfaceis configured to mechanically integrate with a surface of the elongatepolymeric catheter body.

In another embodiment, a catheter pump assembly is provided thatincludes an elongate catheter body, a metallic tubular member, and firstand second mechanical interfaces. The elongate catheter body has aproximal portion and a distal portion. The metallic tubular member isdisposed at least partially distally of the elongate catheter body. Thefirst mechanical interface has a first portion joined to the distalportion of the elongate catheter body and a second portion welded to themetallic tubular member. The second mechanical interface is disposed onan outside surface of the catheter pump assembly. The second mechanicalinterface has a deflectable member configured to be disposed adjacent tothe outside surface of the catheter pump assembly in a firstconfiguration. The deflectable member is configured to be disposedinward of the outside surface of the catheter pump assembly in a secondconfiguration. When in the second configuration, the deflectable membermechanically and securely engages the outside surface of the catheterpump assembly with a structure disposed inward of the second mechanicalinterface.

In another embodiment, a method is provided for coupling components of acatheter pump assembly together. An elongate polymeric tubular body isprovided that has a proximal end and a distal end. A metallic tubularbody is provided that has a proximal portion and a distal portion. Amechanical interface having a first interface zone and a secondinterface zone is positioned such that the first interface zone isdisposed over a portion of the elongate polymeric tubular body adjacentto the distal end thereof. The polymer is then caused to flow into thefirst interface zone, whereby the elongate polymeric tubular bodybecomes joined with the first interface zone of the mechanicalinterface. The metallic tubular body is coupled with the secondinterface zone of the mechanical interface.

In one approach, the polymer is caused to flow by heating the elongatepolymeric tubular body to cause at least a portion of elongate polymerictubular body adjacent to the distal end thereof to transition to a statewith low resistance to deformation.

In another embodiment, a catheter pump assembly is provided thatincludes a proximal portion, a distal portion, and a catheter bodyhaving a lumen extending therebetween along a longitudinal axis. Thecatheter pump assembly also includes a torque assembly that has a firstportion disposed in the lumen of the catheter body and a second portiondisposed distal of the first portion. The second portion coupled with animpeller. The torque assembly causes the impeller to rotate uponrotation of the first portion of the torque assembly. The catheter pumpassembly also includes a thrust bearing and a thrust bearing brace. Thethrust bearing is disposed within the catheter pump assembly adjacent tothe distal end of the catheter body. The thrust bearing resists movementof the torque assembly along the longitudinal axis. The thrust bearingbrace is disposed on the outside surface of the torque assembly. Thethrust bearing brace has a distal face that is directly adjacent to aproximal face of the thrust bearing.

In another embodiment, a catheter assembly is provided that includes anelongate flexible body, a torque assembly, a bearing assembly, and asleeve. The elongate flexible body is disposed along a proximal portionof the catheter assembly and has a proximal infusate channel formedtherein. The torque assembly extends through the elongate flexible body.The bearing assembly comprises a housing having an outer surface and abearing surface disposed within the housing. The bearing surfaceprovides for rotation of the torque assembly within the bearing housing.The sleeve comprises and an inner surface configured to be disposed overthe outer surface of the housing of the bearing assembly and a fluidcommunication structure that extends through the walls of the sleeve.The catheter assembly also includes a distal infusate channel in fluidcommunication with the proximal infusate channel, the distal infusatechannel disposed over the outer surface of the bearing housing andthrough side walls of the slot.

In another embodiment, a catheter pump assembly is provided thatincludes a proximal portion, a distal portion, and a catheter bodyhaving a lumen extending along a longitudinal axis between the proximaland distal portions. The catheter pump assembly also includes animpeller disposed at the distal portion and a stator disposed distal ofthe impeller to straighten flow downstream from the impeller. The statoris collapsible from a deployed configuration to a collapsedconfiguration.

In another embodiment, a catheter system is provided that includes anelongate polymeric catheter body, a cannula, and at least one expandablecomponent disposed within the cannula. The elongate polymeric catheterbody has a proximal end and a distal end. The cannula has an expandableportion disposed distally of the elongate polymeric catheter body. Thecatheter system also includes an elongate sheath body that has aretracted position in which the elongate sheath body is proximal of theexpandable portion of the cannula and the at least one expandablecomponent and a forward position in which the elongate sheath body isdisposed over the expandable portion of the cannula and the at least oneexpandable component. A first segment of the elongate sheath bodydisposed over the expandable portion of the cannula and the at least oneexpandable component is configured to resist kinking to a greater extentthan a second segment of the elongate sheath body disposed adjacent tothe first segment.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the subject matter of this applicationand the various advantages thereof can be realized by reference to thefollowing detailed description, in which reference is made to theaccompanying drawings in which:

FIG. 1 illustrates one embodiment of a catheter pump configured forpercutaneous application and operation;

FIG. 2 is a plan view of one embodiment of a catheter adapted to be usedwith the catheter pump of FIG. 1;

FIG. 3 show a distal portion of the catheter system similar to that ofFIG. 2 in position within the anatomy;

FIG. 4 is a perspective view of a distal portion of a catheter assemblyaccording to one embodiment;

FIG. 5 is a perspective partial assembly detail view of a portion of thecatheter assembly of FIG. 4.

FIG. 6 is a cross-sectional view of a portion of a connection zone ofthe catheter assembly of FIG. 4.

FIG. 6A is a schematic view of embodiments of an outer sheath configuredto enhanced delivery and retrieval performance.

FIG. 7 is a perspective view of a distal portion of a catheter assemblyaccording to another embodiment;

FIG. 8 is a perspective partial assembly detail view of a portion of thecatheter assembly of FIG. 7;

FIG. 9 is a detail view of a mechanical interface of a catheterassembly;

FIG. 10 is a cross-sectional view of a portion of a connection zone ofthe catheter assembly of FIG. 9;

FIGS. 11-14 illustrate features of additional embodiments of catheterassemblies having robust mechanical interface; and

FIGS. 15-17 illustrate features of additional embodiments of catheterassemblies having robust mechanical interface.

FIG. 18A is a schematic system diagram of a catheter pump system,according to some embodiments.

FIG. 18B is a schematic side view of a catheter assembly having aproximal sensor assembly and a distal sensor assembly, according to oneembodiment.

FIG. 19 is a schematic side, sectional view of the impeller assemblypositioned at a proper location during a left ventricular assistprocedure.

FIG. 20 illustrates theoretical plots of pressure over time forpressures detected by the proximal sensor assembly and the distal sensorassembly when the impeller assembly is disposed at a proper treatmentlocation.

FIGS. 21A-21C are schematic side, sectional views of the impellerassembly as the clinician advances the impeller assembly through thepatient.

FIG. 21D is a theoretical plot of pressure over time measured by thedistal sensor assembly at the positions illustrated in FIGS. 21A-21B.

FIG. 22A is a schematic side cross-sectional view of a heart having aregion of myocardial infarction.

FIG. 22B is a schematic front cross-sectional view of the heart shown inFIG. 22A.

FIGS. 22C-22E are theoretical, exemplary plots of pressure over time inthe left ventricle of the heart of FIGS. 22A-22B, in accordance withvarious embodiments.

FIG. 23A is a flowchart illustrating a computer-implemented method fordetermining a position of a cannula relative to an anatomy of a patient.

FIG. 23B is a schematic system diagram of a processor configured toprocess signals received from one or more sensor assemblies.

FIG. 24 is a schematic perspective view of a catheter assembly having aproximal sensor assembly disposed near an outlet of a cannula, accordingto some embodiments.

FIG. 25 is a side cross-sectional view of the catheter assembly of FIG.24.

FIG. 26 is a front end, cross-sectional view of the elongate catheterbody shown in FIG. 24.

FIG. 27 is a schematic perspective view of the bearing housing shown inFIG. 25.

FIG. 28 is an image of a cannula having a distal sensor assembly at thefirst distal sensor location shown in FIG. 18B, according to oneembodiment.

FIG. 29 is an image of a cannula having a distal sensor assembly at thefirst distal sensor location shown in FIG. 18B, according to anotherembodiment.

FIG. 30 is a schematic side cross-sectional view of a cannula having adistal sensor assembly at the second distal sensor location shown inFIG. 18B, according to one embodiment.

More detailed descriptions of various embodiments of components forheart pumps, such as heart pumps for heart failure patients, are setforth below.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A high performance catheter pump is desired to provide sufficient outputto approach and in some cases exceed natural heart output. Performanceof this nature can be achieved with inventive components disclosedherein.

FIGS. 1-3 show aspects of a catheter pump 10 that can provide highperformance including flow rates similar to full cardiac output. Thepump 10 includes a motor driven by a controller 22. The controller 22directs the operation of the motor 14 and an infusion system 26 thatsupplies a flow of infusate in the pump 10. A catheter system 80 thatcan be coupled with the motor 14 houses an impeller within a distalportion thereof. In various embodiments, the impeller is rotatedremotely by the motor 14 when the pump 10 is operating. For example, themotor 14 can be is disposed outside the patient. In some embodiments,the motor 14 is separate from the controller 22, e.g., to be placedcloser to the patient. In other embodiments, the motor 14 is part of thecontroller 22. In still other embodiments, the motor is miniaturized tobe insertable into the patient. Such embodiments allow the drive shaftto be much shorter, e.g., shorter than the distance from the aorticvalve to the aortic arch (about 5 mm or less). Some examples ofminiaturized motors catheter pumps and related components and methodsare discussed in U.S. Pat. No. 5,964,694; U.S. Pat. No. 6,007,478; U.S.Pat. No. 6,178,922; U.S. Pat. No. 6,176,848; and all of which are herebyincorporated by reference herein in their entirety for all purposes.

FIG. 3 illustrates one use of the catheter pump 10. A distal portion ofthe pump 10 is placed in the left ventricle LV of the heart to pumpblood from the LV into the aorta. The pump 10 can be used in this way totreat patients with a wide range of conditions, including cardiogenicshock, myocardial infarction, and acutely decompensated heart failure,and also to support a patient during a procedure such as percutaneouscoronary intervention. One convenient manner of placement of the distalportion of the pump 10 in the heart is by percutaneous access anddelivery using the Seldinger technique or other methods familiar tocardiologists. These approaches enable the pump 10 to be used inemergency medicine, a catheter lab and in other non-surgical settings.

FIG. 2 shows features that facilitate small blood vessel percutaneousdelivery and high performance up to and in some cases exceeding normalcardiac output in all phases of the cardiac cycle. In particular, thecatheter system 80 includes a catheter body 84 and a sheath assembly 88.An impeller assembly 92 is coupled with the distal end of the catheterbody 84. The impeller assembly 92 is expandable and collapsible. In thecollapsed state, the distal end of the catheter system 80 can beadvanced to the heart. In the expanded state the impeller assembly 92 isable to pump blood at high flow rates. FIGS. 2 and 3 illustrate theexpanded state. The collapsed state can be provided by advancing adistal end 94 of an elongate body 96 distally over the impeller assembly92 to cause the impeller assembly 92 to collapse. This provides an outerprofile throughout the catheter assembly 80 that is of small diameter,for example 12.5 French as discussed further below. As explained herein,it may be important to measure various properties and/or characteristicsduring a treatment procedure, such as flow rate and pressure. It mayalso be important to use this data to determine a position of theimpeller assembly 92 relative to the anatomy. One or more sensors (e.g.,pressure sensors) can be coupled with portions of the catheter system 80to measure desired properties and/or characteristics.

In some embodiments, the impeller assembly 92 includes a self-expandingmaterial that facilitates expansion. The catheter body 84 on the otherhand preferably is a polymeric body that has high flexibility. When theimpeller assembly 92 is collapsed, as discussed above, high forces areapplied to the impeller assembly 92. These forces are concentrated at aconnection zone, where the impeller assembly 92 and the catheter body 84are coupled together. These high forces, if not carefully managed canresult in damage to the catheter assembly 80 and in some cases renderthe impeller within the impeller assembly 92 inoperable. A reliablemechanical interface is provided to assure high performance. While thisinterface is extremely beneficial for an assembly with an expandableimpeller disposed in an expandable cannula, it also applies toassemblies including a fixed diameter impeller, which may be disposed inan expandable cannula or even in a non-expandable portion in fluidcommunication with an expandable cannula. In one variation, the impelleris disposed proximal of an expandable cannula in a rigid segment (e.g.,a pump ring) and an expandable cannula is provided. The mechanicalinterfaces and inner and outer sheath assemblies facilitate the collapseof the cannula in such embodiments. A further design permits theimpeller to be withdrawn into a rigid structure, e.g., a pump ring, tocollapse the impeller before the cannula is collapsed.

The mechanical components rotatably supporting the impeller within theimpeller assembly 92 permit high rotational speeds while controllingheat and particle generation that can come with high speeds. Theimpeller may be rotated as speeds above 6000 RPM, above 9000 RPM, above10,000 RPM, above 15,000 RPM, above 20,000 RPM, above 25,000 RPM, orabove 30,000 RPM. The infusion system 26 delivers a cooling andlubricating solution to the distal portion of the catheter system 100for these purposes. However, the space for delivery of this fluid isextremely limited. Some of the space is also used for return of theinfusate. Providing secure connection and reliable routing of infusateinto and out of the catheter assembly 80 is critical and challenging inview of the small profile of the catheter body 84.

Various aspects of the pump and associated components are similar tothose disclosed in U.S. Pat. Nos. 7,393,181; 8,376,707; 7,841,976;7,022,100; and 7,998,054, and in U.S. Pub. Nos. 2011/0004046;2012/0178986; 2012/0172655; 2012/0178985; and 2012/0004495, the entirecontents of each of which are incorporated herein for all purposes byreference. In addition, this application incorporates by reference inits entirety and for all purposes the subject matter disclosed in eachof the following concurrently filed applications: application Ser. No.13/802,556, entitled “DISTAL BEARING SUPPORT,” filed Mar. 13, 2013;Application No. 61/780,656, entitled “FLUID HANDLING SYSTEM,” filed onMar. 13, 2013; application Ser. No. 13/801,833, entitled “SHEATH SYSTEMFOR CATHETER PUMP,” filed on Mar. 13, 2013; application Ser. No.13/802,570, entitled “IMPELLER FOR CATHETER PUMP,” filed on Mar. 13,2013; application Ser. No. 13/801,528, entitled “CATHETER PUMP,” filedon Mar. 13, 2013; and application Ser. No. 13/802,468, entitled “MOTORASSEMBLY FOR CATHETER PUMP,” filed on Mar. 13, 2013.

I. Examples of Catheter Assemblies

FIGS. 4-6 show a first embodiment of a working end of a catheterassembly 100 forming a part of one embodiment of the catheter pump 10.The catheter assembly 100 is similar to the catheter system 84 except asdiscussed differently below. The catheter assembly 100 includes anelongate catheter body 104. A proximal end of the catheter body 104 canbe coupled with a motor housing. A distal portion of the catheter body104 is coupled to a cannula 108 configured to house a high flow rateimpeller 112. The exemplary catheter pump can be configured to producean average flow rate of 4 liters/minute or more at physiologicconditions, e.g., at the typical systolic pressure of a patient needingtreatment, such as 60 mmHg. In various embodiments, the pump can beconfigured to produce a maximum flow rate (e.g. low mm Hg) of greaterthan 4 Lpm, greater than 4.5 Lpm, greater than 5 Lpm, greater than 5.5Lpm, greater than 6 Lpm, greater than 6.5 Lpm, greater than 7 Lpm,greater than 7.5 Lpm, greater than 8 Lpm, greater than 9 Lpm, or greaterthan 10 Lpm. In various embodiments, the pump can be configured toproduce an average flow rate at 60 mmHg of greater than 2 Lpm, greaterthan 2.5 Lpm, greater than 3 Lpm, greater than 3.5 Lpm, greater than 4Lpm, greater than 4.25 Lpm, greater than 4.5 Lpm, greater than 5 Lpm,greater than 5.5 Lpm, or greater than 6 Lpm.

In some embodiments both the cannula 108 and the impeller 112 areactuatable from a first configuration for delivery through a patient toa working site to a second configuration for generating high flow at theworking site. The first configuration may be a low profile configurationand the second configuration may be an expanded configuration. The lowprofile configuration preferably enables access via a femoral artery orother peripheral blood vessel without excessive obstruction of bloodflow in the vessel, as discussed further below.

The catheter body 104 preferably has a plurality of lumens, including afirst lumen 140 adapted for housing a drive shaft 144, a second lumen140B for conveying a medical fluid distally within the catheter body104, and a third lumen 140C for anchoring a bearing housing 146 to thecatheter body 104. The drive shaft 144 extends proximally within thecatheter body 104 from the impeller 112. The drive shaft 144 coupleswith the motor at the proximal end and with the impeller 112 at thedistal end thereof. The drive shaft 144 can be formed with any suitablestructure, but should be sufficient flexible to traverse at least from aperipheral (e.g., femoral) artery to a heart chamber, such as the leftventricle, as well as sufficiently durable to rotate at a high speed forseveral hours, for several days, and in some cases, months. The driveshaft 144 can be coupled with an impeller assembly 112 including anexpandable impeller 112A) disposed on a tubular body 112B FIGS. 4 and 6shows these structures. The impeller 112A preferably includes anelastomeric polymer structure that can be formed as a unitary body. Thetubular body 112B can be a metal hypotube. The tubular body 112B can bereceived in a distal portion of the drive shaft 144.

Any suitable material or combination of materials can be used for thecatheter body 104 or catheter bodies 104A and 304 discussed below andprovided in some embodiments. In one embodiment, the catheter body 104has an inner layer 148 surrounding the lumen 140 that comprises highdensity polyethylene (HDPE). For example, Marlex 4903 HDPE can bedisposed about the lumen 140. If a composite structure is used to formthe catheter body 104, the inner layer 148 has a thickness that issufficient to withstand wear caused by interaction with the drive shaft144, which can be rotated at a very high speed in some applications, forexample from 20,000-40,000 revolutions per minute. The inner layer canhave a thickness of 0.003 inches.

The second lumen 140B extends from a proximal end in fluid communicationwith a source of infusate, which can be a medical fluid (e.g., saline),to a distal end adjacent to the impeller assembly 112. For example, thesecond lumen 140B can have an outlet disposed adjacent to a flow channelformed in or about the bearing housing 146. Examples of bearing housingflow channels are shown in FIGS. 5, 10, and in application Ser. No.13/343,618, which is hereby incorporated by reference. In one embodimentof the catheter body 104A, the second lumen 140B is generallycircumferentially elongated, for example having two sides that arecurved with an arc length of about 0.030 inches and two sides that arestraight, disposed along a radial direction of the catheter body 104 andabout 0.010 inches in length. A proximal end of the second lumen 140B iscoupled with a port, which may be similar to the luer 145 in FIG. 2, orother fluid connection device. Any suitable connection between a portand lumen can be used, e.g., a skived connection can be used.

The third lumen 140C can be used to enhance the security of theconnection between the catheter body 104, 104A and the bearing housing146. For example, the third lumen 140C can be sized to receive aplurality of, e.g., two, pull wires 160. The pull wires 160 can take anysuitable form, but preferably are sized to be easily received within thelumen 140C. In one embodiment, the lumen 140C is spaced apart from butabout the same size as the second lumen 140B and the pull wires aregenerally rectangular in shape, e.g., having a thickness of about 0.005inches and a width of about 0.010 inches. The pull wires 160 can beformed of any material that is sufficiently rigid in tension, e.g., ofstainless steel with pull strength of at least about 300 ksi. In onearrangement, the pull wires 160 extend at least about three inches intothe elongate body 104 in the third lumen 140C and extend out of thethird lumen 140C to overlay the bearing housing 146 as shown in FIG. 5.

FIG. 6 shows one approach to compactly arranging the pull wires 160 andstructure coupled together thereby. In particular, a proximal portion160A of the wires is received within a distal length of the third lumen140C and a distal portion 160C of the wires is disposed distal of thecatheter body 104. A transition 160B is provided between the zones 160A,160C causing the proximal portion 160A to be disposed closer to thelongitudinal axis of the impeller catheter assembly 100 than is thedistal portion 160C. This permits the outer surface of the catheter body104 to be closer to the longitudinal axis of the catheter assembly 100than if the pull wires were straight with the distal portion 160C in thesame position as illustrated.

Providing a plurality of pull wires provides redundancy in theconnection between the catheter body 104, 104A and the bearing housing146. In some cases, this redundancy is not needed and a single wire canbe used. The redundancy is beneficial, however, because substantialtension force is applied at this connection point when the expandablecannula 108 is collapsed. In one technique relative motion is providedbetween the catheter body 104, 104A and an outer sheath disposed overthe catheter body until the outer sheath slides over a proximal portionof the cannula 108. Further relative motion causes the cannula 108 to becompressed, but not without a substantial force being applied thereto.This force is born at several points, including at the junction betweenthe catheter body 104, 104A and the bearing housing 146. Disconnectionof the bearing housing 146 would be problematic, requiring complexprocedures to extract the disconnected distal working end of thecatheter assembly 100.

The pull wires 160 preferably are located close together on the sameside of the catheter body 104, 104A. This arrangement enhances bendingflexibility, which is beneficial if tortuous vasculature must betraversed to deliver the catheter assembly 100 to a treatment site,e.g., a heart chamber. FIGS. 12-14 illustrate other techniques forenhancing the security of the connection of the bearing housing 146 to acatheter body.

In some embodiments, placing a radiopaque marker on a distal portion ofthe catheter assembly 100 is advantageous to confirm the location of theworking end, e.g., of the cannula 108 and/or impeller 112 prior toand/or after deployment.

Gross mechanical properties of the catheter body 104 can be varied alongthe length thereof to provide appropriate flexibility andmaneuverability within the vasculature to facilitate delivery andoperation of the catheter pump into which the catheter assembly 100 isincorporated. For example, in one embodiment, the catheter body 104 isstiffest near the distal end where the catheter body 104 is joined tothe working end. In one embodiment, a distal section of the catheterbody 104 comprises a material, such as Pebax, having a hardness of about72D. A proximal section of the catheter body 104 comprises a material,such as Vestamid having a hardness greater than about 72D. Between theserelatively hard sections ends, a middle section of the catheter bodycomprises a material having a lower hardness, e.g., MX1205 Pedbax. Thelow hardness section provides a softer structure in the vicinity of theaortic arch, where the catheter will be consistently resting on thevessel wall. One or more intermediate hardness sections can be providedbetween the distal, proximal and middle sections. These arrangements arealso relevant to the other inner catheter bodies discussed herein,including bodies 104A, 304.

Alternatively, or in addition to these features, the catheter body 104can have different diameters along its length to provide severalimportant performance benefits. The diameter of a proximal portion ofthe catheter body 104 can be relatively large to enhance pushability andtrackability of the catheter assembly 100. The diameter of a distalportion of the catheter body 104 can be relatively small to enhanceflexibility of the distal tip and also to match the profile of thebearing housing 146 such that the lumens 140B align with flow channelsat least partly defined by the bearing housing (e.g., the slots 220discussed below). The enlarged diameter and enhanced hardness at theproximal end both contribute to the maneuverability of the catheterassembly 100. These arrangements are also relevant to the other innercatheter bodies discussed herein, including bodies 104A, 304 and thecatheter assemblies 100A, 300, and 400 (discussed below).

In addition to the foregoing structures for varying the stiffness alongthe length of the catheter body 104, a separate stiffening component,such as a braid 188, can be disposed in the catheter body 104, 104A. Inone embodiment, a 0.001 inch by 0.003 inch flat wire of 304V stainlesssteel is embedded in the catheter body 104, 104A and the braid includesa 70 ppi configuration. The braid 188 can be positioned in any suitablelocation, e.g., between an inner layer 148 and an outer layer, as shownin FIG. 9 of the drawings.

As discussed above, the catheter assembly 100 preferably also includesan outer sheath or sheath assembly 88 provided over the elongate body104, 104A to aid in delivering, deploying and/or removing the impeller112. The outer sheath 88 can include an elongate body 96 comprising aninner surface surrounding a lumen disposed therein. The inner lumen cancomprise a low friction material or layer. For example, a thickness ofPTFE can be provided adjacent the inner lumen. In one embodiment, one ormore separate materials can be provided at an outer surface of theelongate body 96.

The elongate body 96 preferably is connected at the proximal end with aproximal hub and/or a suitable connector, such as a Tuohy Borstconnector. The proximal hub can include a luer fitting.

The outer sheath 88 also may have varied hardness or other grossmechanical properties along its length to provide appropriateflexibility and maneuverability within the vasculature to facilitatedelivery and operation of the catheter pump into which the outer sheathis incorporated, and also to facilitate collapse of the cannula 108after deployment thereof. FIG. 6A illustrates schematically bulkproperty variation in two embodiments of the sheath assembly 88. Inparticular, an elongate body extending between the proximal and distalends of the sheath assembly 88 has different hardness at differentlocations along the length. The different hardnesses enhance themaneuverability of the sheath assemblies 88A, 88B to minimize kinking ofthe elongate body as the catheter assembly 100 is tracking toward theheart and/or when the elongate body is used to collapse an expandablecannula or impeller, as discussed elsewhere herein.

The elongate body of the sheath assembly 88A has a proximal portion “A”with a highest hardness. The proximal portion A can comprise vestamid orother similar material. A portion “B” distal of the proximal portion Aand residing over a zone of the cannula in which the impeller I and thedistal bearing support S (if present) are housed can have a hardnessthat is lower than that of the portion A. Portion B can comprise 55Dpebax. A portion “C” disposed distal of the portion B can comprise amaterial with the lowest hardness of the elongate body of the sheathassembly 88A, e.g., can comprise MX1205. A portion “D” at the distal endof the elongate body of the sheath assembly 88A can have a relativelyhigh hardness, e.g., 72D pebax. The sheath assembly 88A upon distalmovement over the expanded cannula initially contacts the cannula withthe relatively hard material of portion D. The relatively soft portion Cmay contact the vasculature as the catheter assembly 100 is advanced,and its relatively soft structure is biocompatible. Portion B has ahardness that is high enough to protect the zones I and S of thecannula, impeller, and support. Portion A is the hardest of thematerials used in the sheath assembly 88A, to aid in maneuverability.

The elongate body of the sheath assembly 88B has a proximal portion anddistal bearing zone portion “A” with a highest hardness. The proximalportion A can comprise vestamid or other similar material. A portion “B”between the proximal portion A and the distal bearing zone portion A.The portion B resides adjacent to the transition from the catheter body104 to the cannula proximal portion 116 and can have a hardness that islower than that of the portion A. Portion B can comprise 55D pebax.Portions C and D in the sheath assembly 88B are the same as in thesheath assembly 88A. A portion E is disposed between the portions A andC, e.g., distal of the portion A disposed over the distal bearingsupport. Portion E can include a series of progressively softer lengths,e.g., a first length of 72D pebax, a second length of 63D pebax, and athird length of 55D pebax. Other materials and hardnesses can be usedthat provide good resistance to kinking in the delivery of the catheterassembly 100 and/or in the process of re-sheathing the expanded cannulaand impeller.

FIGS. 7-10 incorporate the discussion above and illustrate additionalfeatures and embodiments. FIGS. 7 and 9 illustrate aspects of amechanical interface between a bearing housing 146A and the catheterbody 104A. In particular, a coupler 200 is provided between the bearinghousing 146A and the catheter body 104A. The coupler 200 (also shown inFIG. 6) is similar to the coupler 628 disclosed in U.S. application Ser.No. 13/343,618, which is hereby incorporated by reference herein. Inthis configuration a thrust bearing 204 is provided in the bearinghousing 146A. In some embodiments, a thrust bearing brace 208 isdisposed just proximal of the thrust bearing 204. The thrust bearingbrace 208 can take any suitable form, but preferably provides a shoulderor other radial protrusion from the outer surface to the impeller shaft112B that abuts a proximal face of the thrust bearing 204. The thrustbearing brace 208 minimizes or completely prevents movement of thethrust bearing 204 on the impeller shaft 112B. Such movement is possiblebecause the impeller on the impeller shaft 112B generates significantdistally oriented thrust. In some assemblies, the thrust bearing 204 isinterference fit onto the impeller shaft 112B. When sized and fitproperly, this connection maintains the relative position of thrustbearing 204 to the impeller shaft 112B under the thrust forces that areapplied. The thrust bearing brace 208 provides redundancy of thisconnection. In one embodiment, the thrust bearing brace 208 comprises ashort hypotube that is coupled with, e.g., laser welded to the impellershaft 112B. The weld completely prevents relative axial movement betweenthe impeller shaft 112B and the thrust bearing brace 208. The abutmentbetween the trust bearing 204 and the thrust bearing brace 208 preventrelative movement between the thrust bearing 204 and impeller shaft 112Bif the coupling between the impeller shaft 112B and the thrust bearing204 loosens.

FIG. 8 shows that an outer surface of the bearing housing 146A can becovered by a cylindrical sleeve 216. The sleeve has at least one slot220 formed therein. The slot 220 can be circumferentially aligned to orotherwise in fluid communication with the second lumen 140B such thatinfusate fluid flowing distally in the lumen enters the slot and can bedirected distally in a space formed between the bearing housing 146A,the sleeve 216 and an outer sleeve, that may be a proximal portion 222of the frame-like structure of the cannula 108. This structure is shownin FIGS. 4 and 5. In FIG. 4, the cannula 108 is displaced proximally toreveal the sleeve 216, which would be covered by a proximal cylindricalportion 222 of the cannula 108 when the catheter assembly 100 isassembled. A difference between the impeller assembly/catheter bodyinterface of the embodiment of FIGS. 4-6 and the embodiment of FIGS.7-11 is that the sleeve 216A includes recess 220A in fluid communicationwith the lumen 140B. The recesses 220A are fluid flow structures. Otherports into the inside of the bearing housing 146A can be accessedthrough apertures 224 that do not extend to the proximal end of thesleeve 216. The apertures are fluid communication structures throughwhich fluid can flow into the bearing housing. Flow from the lumen 104Bto the apertures 224 can be provided through a circumferential spacedefined between the outer surface of the sleeve 216 and an inner surfaceof the proximal portion 222 of the cannula 108. See FIG. 10. In somecases, the apertures 224 are additionally or alternately adapted toreceive components of secondary mechanical interface discussed below. Inother embodiments, troughs are formed in an outer surface of the bearinghousing are enclosed by the inner surface of the sleeve 216 to formenclosed flow channels for infusate.

Catheter pumps incorporating the catheter assembly and variation thereofcan be configured to deliver average flow rates of over 4 liters/minutefor a treatment period. For example, a treatment period can be up to 10days for acute needs, such as patient in cardiogenic shock. Catheterpumps incorporating the catheter assembly 100 or such modificationsthereof can be used for shorter periods as well, e.g., for supportduring high risk catheter or surgical procedures.

Also, catheter pumps incorporating the catheter assembly 100 ormodifications thereof can be used for left or right side heart support.Example modifications that could be used for right side support includeproviding delivery features and/or shaping a distal portion that is tobe placed through at least one heart valve from the venous side, such asis discussed in U.S. Pat. No. 6,544,216; U.S. Pat. No. 7,070,555; and US2012-0203056A1, all of which are hereby incorporated by reference hereinin their entirety for all purposes. For example, the catheter assembly100 or modifications thereof can be configured to be collapsed to bedeliverable through a 13 French introducer sheath and can be expanded toup to 24 French when deployed. In one embodiment, the outer profile ofthe catheter assembly 100 or modifications thereof is approximately 12French, but can be any size that is insertable into a femoral arterywithout requiring surgical cutdown. The catheter assembly 100 can be aslarge as 12.5 F to be inserted through a 13 French introducer sheath.One method involves deployment of the cannula 108, having an expandablenitinol structure, across the aortic valve. In this position, theimpeller 112 can be disposed on the aorta side of the valve and a distallength of the cannula 108 within the ventricle.

In other embodiments, the outer profile of the catheter assembly 100 ormodifications thereof is less than 12 French, e.g., about 10 French. The10 French configuration can be useful for patients with lower flowneeds, e.g., about 3 liters per minute or less at physiologicconditions. In another example, an 8 French configuration can be usefulfor patients with lower flow needs, e.g., about 2 liters per minute orless at physiologic conditions.

FIGS. 11-14 illustrate additional embodiments in which the structuralintegrity of a catheter assembly 300 is enhanced to provide security inconnection with sheathing an expandable portion. FIG. 11 shows that adistal portion of the catheter assembly 300 includes components similarto those hereinbefore described. In particular, the catheter assembly300 includes a catheter body 304, an expandable cannula 308 and anexpandable impeller 312. The catheter body can take any suitable form.In one embodiment, the catheter body 304 has variable hardness along itslength.

The cannula 308 includes a self-expanding structure enclosed in apolymeric film. The self-expanding structure can be a distal portion ofa member having a non-expanding tubular portion 316 proximal of theself-expanding structure. The tubular portion 316 plays a role inanchoring the cannula 308 to the catheter body 304.

FIG. 11 shows that a support member 328 can be positioned within thecannula 308 to prevent unacceptable variance in the gap between the tipof the impeller 312 and the inside surface of the cannula. More detailsof this structure are set forth in concurrently filed application Ser.No. 13/802,556, entitled “DISTAL BEARING SUPPORT,” filed on Mar. 13,2013, which is incorporated hereby by reference herein for all purposes.Successful collapse of the cannula 308, the impeller 312, and thesupport 328 focuses forces on a joint between the cannula 308 and thecatheter body 304.

FIGS. 11-14 illustrate features that enhance the security of theconnection catheter body 304 and the cannula 308. In FIG. 11, noseparate structure is shown between the catheter body 034 and thenon-expanding tubular portion 316. These structures are joined in othermanners, such as indirectly by the force transfer capability of the pullwires discussed above and/or by an adhesive. In FIG. 12, the distal endof the catheter body 304 is coupled with a ferrule 336. The ferrule 336is an example of a structure to mechanically join the catheter body 304to the cannula 308. In one embodiment, the ferrule 336 includes a distalzone 340 for mechanically joining the ferrule 336 to the catheter body304. The distal zone 340 is also configured to mechanically couple withthe cannula 308, for example by welding. A plurality of apertures 344 isprovided in one embodiment for mechanically joining the ferrule 336 tothe catheter body 304. The apertures 344 enable the material of thecatheter body 304 to extend into the distal zone 340. In one techniquethe ferrule 336 is disposed over the catheter body 304 which extendsinto the apertures 344.

The apertures 344 can be arranged in multiple zones. In one embodiment afirst zone is disposed distally of the second zone. The first zone canbe disposed adjacent to the distal end of the ferrule 336 and the secondzone is disposed proximal of the first zone. The first zone can includefour apertures 344A spaced evenly about the periphery of the body of theferrule. The second zone can include a plurality of (e.g., four)apertures 344B spaced evenly about the periphery of the body of theferrule 336. A specific advantageous embodiment provides four apertures344B in the second zone. The apertures 344B of the second zone can bespaced evenly about the body of the ferrule 336. Preferably theapertures 344 of the first and second zones are offset to provide agreat deal of redundancy in the security of the connection of thecatheter body 304 to the ferrule 336. For example, the apertures 344 inthe first and second zones can be offset by one-half the circumferentialdistance between adjacent apertures 344.

The ferrule 336 also includes a proximal zone 348 disposed proximally ofthe aperture 344. The proximal zone 348 preferably is configured toprovide an excellent fluid seal between the ferrule and thenon-expandable tubular portion 316 of the cannula 308. In oneembodiment, the proximal zone 348 includes a plurality of recesses 352in the outer surface of the proximal portion 348. The recesses 352 cantake any form consistent with good sealing, and in one embodiment therecesses are turns of a continuous helical groove in the outer surfaceof the ferrule 336. The helical groove is configured to receive asealant that can bridge from the base of the grooves to the innersurface of the proximal portion 316 of the cannula 308. In oneembodiment, the sealant includes an adhesive that can flow into thehelical groove and be adhered to the inner surface of the proximalportion 316 of the cannula 308.

Although the weld and adhesive that can be formed or disposed betweenthe ferrule 336 and the proximal portion 316 of the cannula 308 canprovide excellent security between these components of the catheterassembly 300, a supplemental securement device 360 can be provided insome embodiments. FIG. 11 illustrates one embodiment in which amechanical securement device 360 is provided. The mechanical securementdevice 360 includes a cantilevered member that can be deformed from thenon-expandable proximal portion 316 of the cannula 308 intocorresponding recesses disposed inward of the securement device.

In one embodiment, a recess 364 is provided within the catheter assembly300 to receive the securement device 360. The recesses 364 can be formedin an internal structure disposed within the proximal portion 316. In afirst variation, a sleeve 368 is provided immediately within thenon-expandable proximal portion 316 of the cannula 308. The sleeve 368is provided and fills the volume between a bearing housing 372 and theproximal portion 316. The bearing housing 372 facilitates rotation ofthe impeller shaft and the flow of infusate. The sleeve 368 has slotsand/or other fluid communication structures formed therein that directflow from channels in the catheter body 308 to flow channels in thebearing housing 372. In one embodiment, the sleeve 368 has a pluralityof small apertures that are disposed between flow slots. The aperturesand slots can be similar is shape and form to the apertures 224 andslots 220 discussed above.

In other embodiment, apertures can be formed in the bearing housing 372.For example, the bearing housing 372 can have a plurality of channelsaligned with flow passages in the catheter body 304. In such embodiment,apertures for receiving the securement device 360 can be provideddirectly in the bearing housing 372. In another variation, apertures areprovided that extend through the sleeve 368 and into the bearing housing372.

Modifications of catheter pumps incorporating the catheter assembly 300can be used for right side support. For example, the elongate body 304can be formed to have a deployed shape corresponding to the shape of thevasculature traversed between a peripheral vascular access point and theright ventricle.

Any suitable manufacturing method can be used to cause a portion of thecatheter body 304 to be disposed in the apertures 344. For example, inone the catheter body 304 and the cannula 308 are to be joined. Thecannula 308 has the tubular portion 316 which is to be disposed over thecatheter body 304. The ferrule 336 is a metallic body that is animportant part of one form of a mechanical interface. The ferrule 336has an inner surface and apertures 344 that act as a first interfacezone and an outer surface that acts as a second interface zone. Theferrule 336 is positioned such that the inner surface is disposed overthe outer surface of short length of the catheter body 304 adjacent tothe distal end thereof.

In one technique, the outer surface of the catheter body 304 ismechanically coupled to the ferrule 336 by a process that involvesheating. The distal portion of the catheter body 304 and the ferrule 336are heated sufficiently to cause at least a portion of the catheter bodyto transition to a state with low resistance to deformation. The lowresistance state can be a fluid state or just a state in which thematerial of the catheter body 304 if more malleable. In the state havinglow resistance to deformation, the catheter body 304 flows through orprotrudes into the apertures 344. Because the material is formedcontinuously from a location inside the inner surface of the ferrule tooutside the inner surface, a strong mechanical coupling is providedbetween these components.

The tubular portion 316 of the cannula 308 can be coupled with theferrule 336 by any suitable technique. In one embodiment, the tubularportion 316 and the ferrule 336 are indirectly coupled through sleeve368 discussed more below. In particular, the distal end of the ferrule336 can be welded to the proximal end of the sleeve 368 and a secondconnection can be provided between the portion 316 and the sleeve asdiscussed elsewhere herein. In another embodiment, the ferrule 336 canbe directly connected by a suitable technique, such as welding ifsuitable materials are provided. These structures are also illustratedin FIG. 16 below, which shows further details of the connection by theferrule 336.

The foregoing technique of heating the catheter body 304 to cause thematerial thereof to be coupled with the proximal portion 160A of thepull wire(s) 160. Another technique for joining the pull wires 160 tothe catheter body 304 is by an epoxy or other adhesive at the proximalend of the wires and/or catheter body 304. A distal section of the pullwires 160 within the catheter body 304 can be left un-adhered to thecatheter body, such that this section of the pull wires 160 can moverelative to the catheter body or “float” to enhance flexibility of thedistal portion of the catheter body in some embodiments. The proximalportion 160A provides a first interface zone of a mechanical interfacebetween the catheter body 104 and the bearing housing 146. The distalportion 160C provides a second interface zone that can be coupled withthe bearing housing 146 by a suitable technique, such as welding. Inanother embodiment, the sleeve 216, 216A is formed of a material towhich the pull wires can be welded or otherwise mechanically secured.

FIG. 11 illustrates an additional optional feature that can facilitatetreatment with a catheter pump including the catheter assembliesdisclosed herein or any of the pumps discussed in U.S. application Ser.Nos. 13/343,618 and 13/343,617, which are hereby incorporated herein byreference. A deployment system is provided by combining the catheterassembly 300 (or any other discussed or claimed herein) with a guidewire guide 240. The guide wire guide 240 can be configured as a smallelongate tubular member sized to be advanced in a lumen formed in thedrive shaft 144. The guide wire guide 240 includes a lumen that is sizedto receive a guidewire (not shown). The wall thickness of the guide wireguide 240 is thin enough to fit within the allotted tolerance fortracking the catheter assemblies discussed herein through thevasculature. The guide wire guide 240 wall thickness is also thin enoughto permit the guide wire guide 240 to be withdrawn from between theguide wire and the catheter assembly once the guidewire is in placewithout damaging either of these structures or disrupting the positionof guidewire excessively. In various embodiments, the guide wire guide240 includes a self healing member that remains within the catheterassembly when the tubular portion is removed. The self-healing memberhas an end wall that re-seals when the guidewire is removed. Thus, theguide wire guide 240 facilitates loading the catheter assemblies onto aguidewire for a percutaneous delivery within a patient.

II. Examples of Stator Assemblies

FIGS. 15-17 show details of a catheter assembly 400 having a statorassembly 402 disposed in a distal portion thereof. The stator assembly402 enhances the performance of a catheter pump including the catheterassembly 400. The stator assembly 402 can include a stator blade body404 having one or a plurality of, e.g., three, blades 408 extendingoutwardly from a central boy 412. The stator blade body 404 is at adownstream location of the impeller 312. In a percutaneous leftventricle application, the stator blade body 404 is disposed proximal ofthe impeller 312. In a percutaneous right ventricle application, thestator blade body 404 is located distal of the impeller 312. In atransapical approach to aid the left ventricle, which might be providedthrough ports in the chest wall or via thoracotomy or mini-thoracotomy,the stator blade body 404 is disposed distal of the impeller 312.

The stator blades 408 are configured to act on the fluid flow generatedby the impeller 312 to provide a more optimal fluid flow regimedownstream of the stator assembly 402. This fluid flow regime cancorrespond to a more optimal fluid flow regime out of the outlet of thecatheter pump. The stator blades 408 preferably convert at least theradial component of flow generated by the impeller 312 to a flow that issubstantially entirely axial. In some cases, the stator blades 408 areconfigured to reduce other inefficiencies of the flow generated by theimpeller 312, e.g., minimize turbulent flow, flow eddies, etc. Removingthe radial components of the flow can be achieved with blades that areoriented in an opposite direction to the orientation of the blades ofthe impeller 312, for example, clockwise versus counterclockwiseoriented blade surface.

While the stator blades 408 act on the flow generated by the impeller312, the fluids also act on the stator assembly 402. For example, thestator blade body 404 experiences a torque generated by the interactionof the blades 408 with the blood as it flows past the stator assembly402. A robust mechanical interface 420 is provided between the centralbody 412 and a distal portion of the catheter assembly 400. A bearinghousing 424 is provided that is similar to the bearing housing 372,except as described differently below. The bearing housing 424 includesan elongate portion 428 that projects into a lumen of the central body412. The elongate portion 428 preferably has an outer periphery that issmaller than an outer periphery of a portion of the bearing housing 424immediately proximal of the elongate portion 428.

This structure provides an interface 432 disposed between the elongateportion and the portion just distal thereto. The interface 432 can be ashoulder having a radial extent that is approximately equal to that ofthe central body 412. In some embodiments, a flush surface is providedbetween the outer surface of the central body 412 and a distal outersurface of the sleeve 368 such that the radial extent of the shoulder ofthe interface 432 is less than that of the central body 412 by an amountapproximately equal to the thickness of the sleeve 368. The interface432 can also or alternately includes an engagement feature between theinner surface of the lumen of the central body 412 and the outer surfaceof the elongate portion 428. In one embodiment, the outer surface of theelongate portion 428 has a helical projection or groove and the centralbody 412 has corresponding and mating helical grooves or projections.These features can be or can be analogous to screw threads. Preferablythe helix portion is arranged such that the torque felt by the statorassembly 402 generates a tightening of the engagement between theelongate portion 428 and the central body 412. The projections orgrooves in the central body 412 can be formed by molding the centralbody 412 over the elongate projection 428.

A small gap is provided between the stator assembly 402 and the impeller312 such that no or minimal contact is provided between thesecomponents, but the flow between the blades of these structures smoothlytransitions between the blades thereof. Such an arrangement is useful inthat the impeller 312 rotates at more than 10,000 RPM while the statorassembly 412 is stationary.

While the robust mechanical interfaces between the catheter body 104 andthe cannula 108 is important to the catheter assembly 300 the interfaceis even more important in certain embodiments of the catheter body 400that are actuated to a collapsed state prior to being removed from thepatient. In such embodiments, the deployed working end preferably iscollapsed, including the cannula 308, the stator blade body 404, and theimpeller 312. This can be done by providing distal relative motion ofthe sheath assembly 88. The forces applied by the sheath assembly 88 tothe catheter body 400, stator blade body 404, and the impeller 312 andfocused at the mechanical joints are enhanced due to the presence of thestator blade body 404.

One will appreciate from the description herein that the catheterassembly may be modified based on the respective anatomy to suit thedesired vascular approach. For example, the catheter assembly in theinsertion state may be shaped for introduction through the subclavianartery to the heart. The catheter pump may be configured for insertionthrough a smaller opening and with a lower average flow rate for rightside support. In various embodiments, the catheter assembly is scaled upfor a higher flow rate for sicker patients and/or larger patients.

III. Examples of Sensors for Catheter Pumps

In various embodiments, it can be important to measure variousproperties and/or characteristics during operation of a catheter pump orcatheter assembly. For example, it can be desirable to measure localproperties of the fluid flow such as pressure, flow rate, turbulence,viscosity, and/or chemical or biological composition. It may also bedesirable to measure other properties including, but not limited to,properties based on the surrounding anatomy, cardiovascular system, orpulmonary system. It may also be desirable to measure changes to theseproperties. For example, it may be desirable to measure and record therate of change or minimum and maximum values within a period of time.Suitable devices for measuring the local properties include, but are notlimited to, sensors to measure pressure, flow, and blood chemistry.Exemplary flow rate sensors include a differential pressure flowmeter, avelocity flowmeter, a positive displacement flowmeter, a mass flowmeter,and an open channel flowmeter. Exemplary flow sensors include Dopplerultrasound and time of flight. Additional details regarding exemplarysensor assemblies are provided below.

In various embodiments, the position and/or orientation of the impellerassembly of a catheter pump relative to the anatomy can be determinedusing measured parameters. For example, as explained in more detailherein, in left ventricular assist devices (LVADs), a desired targetposition for an exemplary catheter pump is such that the aortic valve isbetween the inlets and the outlets of the catheter pump. If the catheterpump is positioned too far within the left ventricle or too far withinthe aorta, then the flow rate may be meaningfully reduced and patientoutcomes may be negatively affected. Typically the catheter pump ispositively placed in a target position under fluoroscopy. Duringoperation, however, the pump can become displaced because of severalfactors including operation of the pump and forces on the pump from theaortic valve, aortic walls, and left ventricle. It can be desirable tocontinuously monitor the position of the impeller assembly of thecatheter pump relative to the anatomy to ensure continued alignment at atarget position. Although the examples explained herein are illustratedand described with respect to LVADs, it should be appreciated thatsimilar sensor configurations can be used with other cardiac assistdevices (such as right ventricular assist devices, or RVADs, orbiventricular assist devices, or BiVADs) and/or other types of catheterassemblies.

In some embodiments, a catheter assembly can include a cannula having aproximal portion and a distal portion. A proximal sensor assembly can bedisposed near the proximal portion of the cannula. In some embodiments,a distal sensor assembly can also be disposed near the distal portion ofthe cannula. In some embodiments, only a proximal sensor assembly can beused, while in other embodiments, only a distal sensor assembly can beused. In an exemplary embodiment, the catheter pump is configured forpositioning across the aortic valve such that blood is moved from theleft ventricle to the ascending aorta. An optional proximal sensorassembly positioned proximal the valve measures a fluid property (e.g.,pressure) in the aorta of the patient. An optional distal sensorassembly positioned distal the valve measures a fluid property (e.g.,pressure) in the left ventricle. In one embodiment, the catheterassembly includes at least two sensors and calculates a difference inthe measured values between the at least two sensors. In otherprocedures, however, it should be appreciated that the proximal anddistal sensor assemblies can measure other properties and/orcharacteristics, such as flow rate, chemical/biological composition,etc. Further, in other procedures, the proximal and/or distal sensorscan be configured to be disposed in other parts of the anatomy or otherchambers of the heart (such as the right atrium, right ventricle, and/orpulmonary artery for right-side assist procedures).

In a typical procedure, a physician may confirm placement at a targetlocation using conventional techniques like fluoroscopy or x-ray. Theone or more sensors then transmit a baseline signal to a controllerindicative of proper positioning of the catheter pump. The controllercan include a processing unit configured to store and analyze a baselinesignature based on the signal received from the sensor(s), which can berepresentative of proper placement of the distal portion of the catheterpump, e.g., such that the aorta straddles the inlets and outlets of theimpeller assembly for an exemplary left-side assist procedure. If theimpeller assembly becomes misaligned or otherwise out of positionrelative to the anatomy, then the signal transmitted by the sensor(s) isexpected to change. The processing unit which processes the signaldetects an event based on the signal. The processor may detect adisturbance signature. In one example, the processor may identify asignature in the sensor signal indicative of improper placement of thecatheter pump. In one example, the processor identifies an event basedon one or more of the following factors: an amplitude, a maximum value,a minimum value, a frequency, a wavelength, a shape of the signalwaveform, a rate of change (first derivative) of a characteristic of thesignal, whether the signal is positive or negative, and whether thesignal changes between positive and negative. Various signal processingtechniques and/or look-up tables as will be understood from thedescription herein can be used to determine analyze the signal. In oneexample, the processor compares the received signal to the baselinesignature and identifies a disturbance event (e.g. malpositioning of thepump) when the received value is sufficiently different from thebaseline signature. In one example, the received signal is sufficientlydifferent when the comparison value exceeds a predefined threshold. Inthe case of an event detection, the controller can send a notificationto the clinician. The clinician can accordingly reposition the workingend of the catheter pump in the proper orientation.

In various embodiments, the processor makes use of heuristics, fuzzylogic, neural networks, machine learning, and/or other advancedprocessing and learning techniques. In various embodiments, theprocessor evaluates the signal information using artificial intelligenceincluding inference rules related to the target location and/or positionin the pathway to the target location, comparisons to information in adatabase, and probabilities, among others.

The processor may improve or learn over time. In one example, theprocessor detects a fault in the pump based on the received signal andreturns an alarm notification for the clinician, e.g., by way of a userinterface on a console. In one implementation, the processor detects thefault in the pump using stored values such as expert data. If theprocessor determines that the pump is properly positioned, but adetermined flow rate is below an expected value, the processor mayidentify a failure in the pump. In another example, the processoridentifies a mechanical failure and displays an alarm representative ofthe failure mode to the physician. The physician resets the alarm,indicating the pump is working properly, and after one or more resetsthe processor learns that the circumstances or parameters are a falsepositive. Likewise, the processor can use past information to improvethe accuracy of its event detection techniques.

In various embodiments, the catheter pump system includes at least onesensor to measure pressure and/or flow rate. In one embodiment, thesystem includes a pressure sensor to measure pressure as a proxy forflow rate. For example, the system can determine a flow rate based onthe measured pressure using a standard pressure-flow curve. In variousembodiments, the processor makes use of the pressure and/or flowpattern. For example, the flow pattern in the ventricle is expected tobe different than the atria and blood vessels, not just in absolutevalues, but also in flow patterns. The ventricle experiences distinctflow patterns commensurate with the cardiac cycle. Similarly, the flowon the venous side of the vasculature is relatively low pressure andturbulent compared to the arterial side. The processor can make use ofsuch knowledge of the physiology to identify where the sensor is locatedand the local conditions.

In various embodiments, the processor makes use of information fromadjunctive devices like a heart rate monitor, ECG or EEG, blood glucosemonitor, or accelerometer. The processor may make use of inputs from aphysician (e.g. hematocrit or pulmonary capillary wedge pressure).

In various embodiments, the processor makes use of biomarkers. Forexample, lactate dehydrogenase (LDH) and brain natriuretic peptide (BNP)can be used as biomarkers for developing a thrombosis risk index. Theprocessor can identify a particular event based on the thrombosis riskindex. For example, if the thrombosis risk index suggests a highlikelihood of thrombus while the flow rate is significantly below anexpected value and the current to the pump spikes, the processor maydetermine that thrombus is present in the pump.

In various embodiments, the processor makes use of various inputsincluding, but not limited to, the signal from the sensor(s), motorcurrent, motor voltage, and back electromagnetic force (emf) from themotor.

A. Overview of Catheter Pump Systems Having One or More SensorAssemblies

FIG. 18A is a schematic system diagram of a catheter pump system 501,according to some embodiments. The system 501 can include a catheterassembly 500. In various embodiments, the catheter assembly 500 can bethe same as or similar to the catheter assemblies disclosed above withrespect to FIGS. 1-17. In addition, as explained below, the catheterassembly 500 can include a proximal sensor assembly 521 and/or a distalsensor assembly 524. The proximal and/or distal sensor assemblies 521,524 can be configured to detect a suitable fluid property orcharacteristic, such as pressure, flow rate, etc. In some embodiments,for example, the proximal and/or distal sensor assemblies 521, 524comprise pressure sensors, e.g., optical pressure sensors.

The system 501 can include a controller 502 having a processing unit503. One will appreciate, however, that the processor unit can beseparate from the controller. The processor unit can also be placedanywhere, including in the body. The proximal and distal sensorassemblies 521, 524 can be in data communication with the controller502. For example, for optical pressure sensors, the proximal and distalsensor assemblies 521, 524 can be in optical communication with thecontroller 502 by way of one or more optical fibers. The controller 502may be physically coupled to or housed in a console in somearrangements. The processing unit 503 can include one or more processorsprogrammed to perform methods that are encoded on software stored and/orcompiled on any suitable type of storage medium, such as anon-transitory computer-readable storage medium. Any suitable processorcan be used in the processing unit 503, including, but not limited to,field programmable gate arrays (FPGAs), application-specific integratedcircuits (ASICs), complex programmable logic devices (CPLDs),programmable logic arrays (PLAs), general purpose processors,microprocessors, or other similar processing devices. Thecomputer-implemented instructions may be stored on any suitable storagemedium, such as optical storage devices, volatile or non-volatile memorydevices, RAM, EEPROM, ROM, etc.

The controller 502 can electrically communicate with a user interface505. The user interface 505 can include visual (e.g., a display), audio,and/or other outputs for notifying the clinician of various eventsduring a treatment procedure. For example, the controller 502 cancommunicate various properties or characteristics of the treatmentprocedure to the user interface 505, which can notify the clinician ofsuch properties or characteristics. In some embodiments, the controller502 can determine whether or not the catheter assembly 500 is properlyor improperly positioned relative to the patient's anatomy, and the userinterface 505 can notify the clinician about the proper or improperposition. For example, the user interface can signal to the clinicianthat the catheter assembly needs to be pushed in further or retracted.The user interface 505 can also include one or more input devicesconfigured to receive instructions from the clinician, for example, forinitiating, modifying, and/or terminating a treatment procedure.

FIG. 18B is a schematic side view of a catheter assembly 500 having aproximal sensor assembly 521 and a distal sensor assembly 524, accordingto one embodiment. As with the embodiments disclosed above with respectto FIGS. 1-17, the catheter assembly 500 can include an elongatecatheter body 504 having one or more lumens therethrough. The elongatecatheter body 504 can be configured to provide fluid, optical, and/orelectronic communication to/from outside the patient's body to thesensor (e.g. at the working end of the catheter assembly 500). Animpeller assembly 592 can be coupled to a distal end portion of theelongate catheter body 504. The connection between the impeller assembly592 and the catheter body 504 can be provided using any suitablemechanism, such as the mechanisms disclosed above. The impeller assembly592 can comprise an impeller 512 disposed at least partially within acannula 508. As explained above, the cannula 508 and/or the impeller 512can have a compact, stored configuration, in which the impeller assembly592 can be inserted percutaneously into the vascular system of thepatient. The cannula 508 and/or the impeller 512 can have an expandedconfiguration, in which the cannula 508 and/or the impeller 512 can pumpblood to assist the heart in providing adequate circulation within thepatient's body.

The catheter assembly 500 can include a tip member 526. The tip member526 can be any suitable tip, such as the elongate and rounded tip member526 shown in FIG. 18B. The tip member 526 can comprise a relatively softand/or flexible material to help guide the impeller assembly 592 withinthe vasculature of the patient. The soft tip member 526 can assist inpreventing damage to the anatomy caused by impact of the tip againsttissue. In some embodiments, the tip member 526 can have a distalopening 527, through which various system components can be inserted, asexplained herein. In some embodiments, a distal lumen 525 can extendpast the impeller 512 between the impeller 512 and the tip member 526.In some arrangements, the distal lumen 525 can pass through the tipmember 526. As shown in FIG. 18B, the distal lumen 525 can be radiallycentered relative to the cannula 508. In other embodiments, the distallumen 525 can be radially offset relative to the cannula 508.

The cannula 508 can include one or more fluid inlets 523 near a distalportion of the cannula 508 and one or more fluid outlets 522 near aproximal portion of the cannula 508. During operation, the impeller 512can rotate, pulling fluid in a proximal direction relative to thecatheter assembly 500. For example, blood can be pulled from a leftventricle through the inlets 523 and can propagate within the cannula508. The blood can exit the cannula 508 through the outlets 522 near theproximal portion of the cannula 508. In still other embodiments,however, blood can flow distally (e.g. in an RVAD configuration).Although a plurality of inlets 523 and outlets 522 are described herein,it should be appreciated that, in other embodiments, there may be onlyone inlet 523 and/or only one outlet 522.

As shown in FIG. 18B, the proximal sensor assembly 521 can be disposednear the proximal portion of the cannula 508, e.g., near the outlets522. The proximal sensor assembly 521 can include a sensor body andsensor (e.g., a pressure sensor) configured to convert detectedproperties of the fluid to a signal readable by the controller 502. Insome embodiments, the sensor can be housed in the sensor body or housingfor protecting the sensor from the anatomy and/or blood. In someembodiments, the sensor is exposed to the fluid to be measured throughan aperture. In some embodiments, the sensor is isolated by a pressuretransmitting medium such as a foam-like material. The proximal sensorassembly 521 can be positioned at any suitable proximal location. FIG.18B illustrates two exemplary suitable proximal sensor locations, afirst proximal sensor location 521A and a second proximal sensorlocation 521B. A suitable sensor (such as a pressure sensor) can bedisposed at one or both of the proximal sensor locations 521A, 521B. Forexample, a pressure sensor can be positioned at the second proximalsensor location 521B, which may be located proximal the outlets 522. Insuch embodiments, the sensor may be disposed through a sensing zone suchas a proximal window in the catheter assembly 500, e.g., a window in theelongate catheter body 504. In such embodiments (e.g., as describedherein with respect to FIG. 21B), the sensor can comprise an elementexposed to fluid flow. Any suitable type of sensor can be employed asunderstood by a skilled artisan, such as a distal end of a fiber opticcable, a resistive sensor, Wheatstone bridge sensor,microelectromechanical systems (MEMS) sensors, acoustic sensor, etc. Forexample, the sensor element can comprise a device that generateselectrical current and/or an optical signal when exposed to pressure,e.g., absolute pressure, differential pressure, and/or pressurefluctuations.

In some arrangements, the first proximal sensor location 521A can bedisposed nearer the outlets 522 than the second proximal sensor location521B. For example, as shown in FIG. 18B, the first sensor location 521Acan be disposed proximate the outlets 522, e.g., substantially alignedwith the outlets 522 along an axial direction in some embodiments. Whenpositioned at the first proximal sensor location 521A, the sensor can bedisposed near a window near the proximal portion of the cannula 508,e.g., near an interface between the cannula 508 and the distal endportion of the elongate catheter body 504 or the fluid outlet. The firstproximal sensor location 521A may provide more accurate fluidmeasurements in some embodiments. The proximity of the first proximalsensor location 521A with the outlets 522 may provide measurements offluid properties (e.g., pressure) as the blood leaves the outlets 522.Improving the accuracy of measurements near the outlets 522 can beadvantageous in estimating the position and/or orientation of theimpeller housing 592 relative to the anatomy.

The distal sensor assembly 524 can be disposed near the distal portionof the catheter assembly 500. As with the proximal sensor assembly 521,the distal sensor assembly 524 can include a sensor body configured toconvert a fluid property (e.g., pressure) to a signal readable by thecontroller 502 (e.g., an optical signal, a voltage, or a current). Thedistal sensor assembly 524 can be disposed at one or more distal sensorlocations. As shown in FIG. 18B, for example, the sensor body of thedistal sensor assembly 524 can be disposed at one or more of a firstdistal sensor location 524A, a second distal sensor location 524B, and athird distal sensor location 524C. The first distal sensor location 524Acan be disposed along an outer wall of the cannula 508 near the inlets523. By contrast, the second distal sensor location 524B can be disposedat a radially central or internal position relative to the cannula 508.For example, in some embodiments, the second distal sensor location 524Bcan be disposed through a window in the distal lumen 525. By beingdisposed near the inlets 523, the first and second distal sensorlocations 524A, 524B can provide accurate fluid measurements (e.g.,pressure measurements) of blood as it flows through the inlets 523.Improving the accuracy of such fluid measurements near the inlets 523can improve the accuracy with which the position of the impellerassembly 592 is measured.

In some embodiments, the distal sensor assembly 524 can be positioned atthe third distal sensor location 524C. The third distal sensor location524C can be disposed at or near a distal-most end of the catheterassembly 500. For example, as shown in FIG. 18B, the third distal sensorlocation 524C can be disposed at the distal end of the tip member 526.In some embodiments, the third distal sensor location 524C can bedisposed at or near the distal opening 527. When positioned at the thirddistal sensor location 524C, the distal sensor assembly 524 can measurefluid properties, such as pressure, at the distal-most portion of theassembly 500, which may be within the left ventricle for left-sideassist procedures.

B. Detecting the Position of the Impeller Assembly Relative to theAnatomy

FIG. 19 is a schematic side, sectional view of the impeller assembly 592positioned at a proper target location during a left ventricular assistprocedure, e.g., at a position and/or orientation at which adequatecardiac assistance is provided to the patient by the impeller assembly592. A human heart 530 having a left ventricle 532, an aorta 531, and anaortic valve 533 is illustrated in FIG. 19. During a left-side treatmentprocedure, the impeller assembly 592 can be inserted through thevascular system of the patient in a compact, stored configuration. Theimpeller assembly 592 can be advanced to the heart 530 and can bepositioned across the aortic valve 533. During normal operation of thecatheter assembly 500, the inlets 523 can be disposed in the leftventricle 532, and the outlets 522 can be disposed in the aorta 531.During insertion of the impeller assembly 592 into the patient, theclinician can use any suitable positioning system (e.g., radiographicmarkers under fluoroscopy, etc.) to ensure that the impeller assembly592 is properly positioned in the heart 530. The inlets 523 and outlets522 can be positioned sufficiently far from the aortic valve 533 suchthat the opening and closing of the valve 533 does not affect or occludethe flow of blood through the cannula 508. Positioning the inlets 523and outlets 522 on opposing sides of the aortic valve 533 can ensurethat blood is freely drawn from the left ventricle 532 and conveyed pastthe aortic valve 533 and into the aorta 531. Thus, when the impeller 512rotates in the cannula 508, blood can be drawn from the left ventricle532 through the inlets 523. The blood can pass through the cannula 508and out from the outlets 522 into the aorta 531. When positioned asshown in FIG. 19, the proximal sensor assembly 521 can measure fluidproperties (e.g., pressure) representative of blood flow through theaorta 531. The distal sensor assembly 524 can measure fluid properties(e.g., pressure) representative of blood flow in the left ventricle 532.When the procedure is completed, the impeller assembly 592 can becollapsed and withdrawn from the patient.

FIG. 20 illustrates theoretical plots of pressure over time for baselinepressures P₁′, P₂′ that may be detected by the proximal sensor assembly521 (top) and the distal sensor assembly 524 (bottom), respectively,when the impeller assembly 592 is disposed at a proper treatmentlocation (such as that illustrated in FIG. 19) and activated atoperational speeds. With respect to the plot at the top of FIG. 20, apressure curve P₁ ⁰ illustrates a theoretical plot of pressure over timein an aorta 531 in a normal human heart 530 without the impellerassembly 592, e.g., during normal operation of the heart. For example,the pressure curve P₁ ⁰ reflects the pulsatility that is generatedduring systole and diastole during normal cardiac activity.

When the impeller assembly 592 is inserted across the aortic valve 533and activated, the proximal sensor assembly 521 may measure a pressurecurve similar to the theoretical, exemplary pressure curve P₁′ shown inthe top plot of FIG. 20. Thus, when positioned across the aortic valve533 (as shown in FIG. 19) in a proper treatment location, the proximalsensor assembly 521 can measure the pressure in the aorta 531. Theoperation of the impeller 508 may create a more continuous flow patternthrough the heart 530 than that illustrated in pressure plot P₁ ⁰, whichis reflected in the relatively smooth, less pulsatile pressure curve P₁′representing pressure in the aorta during treatment. In the pressurecurve P₁′, the impeller 508 is contributing to some of the blood flow,evening out the pressure curves corresponding to blood flow in theaorta. Even though the pressure curve P₁′ is relatively smooth, theproximal sensor assembly 521 may nevertheless be sensitive enough todetect a small amount of pulsatility as the ventricle unloads, which isreflected in the smooth, relatively small peaks shown in FIG. 20. Theaverage pressure of the pressure curve P₁′ may be about the same as theaverage pressure in the pressure curve P₁ ⁰, even though P₁′ illustratesreduced pulsatility.

The bottom plot in FIG. 20 is a theoretical, exemplary pressure curveP₂′ that may be measured by the distal sensor assembly 521 when theimpeller assembly 592 is disposed in a proper treatment position androtated at operational speeds. As explained above, the impeller assembly592 may be in the configuration shown in FIG. 19 when in a propertreatment position, in which the distal sensor assembly 521 is disposedin the left ventricle 532. As with the aortic pressure plots describedabove, the bottom plot of FIG. 20 also illustrates a theoreticalpressure curve P₂ ⁰ representing the pressure in the left ventricle 532during a normal cardiac cycle (e.g., without the impeller assembly 592).As shown in the curve P₂ ⁰, the flow through the left ventricle 532without assistance from the impeller 508 typically exhibits pulsatility,e.g., relatively large pressure peaks as the ventricle unloads. Forexample, for patients who have experienced a heart attack or othercardiac problems, as shown in the curve P₂ ⁰, pressure in the leftventricle 532 may be in a range of between about 15 mmHg to about 20mmHg before systole, and may peak to over 100 mmHg after systole. Insome patients, the pressure in the left ventricle 532 may be in a rangeof about 6 mmHg to about 20 mmHg, or between about 11 mmHg to about 15mmHg before systole.

By contrast, when the impeller is properly positioned (such that theoutlets 523 and distal sensor assembly 524 are in the left ventricle532) and the impeller is activated to rotate at operational speeds, thepump can reduce loading on the left ventricle. By example, if it isassumed the ventricle has a volume such that it pumps 5.5 Lpm at fullcardiac output and an exemplary pump can flow 4 Lpm, the heart willstill pump 1.5 Lpm even when the pump is operating. If it is furtherassumed that the heart rate is 150 bpm, then it can be determined thatonly 1.5 L is expelled by the natural contractility of the ventricle forevery 150 beats or 1 cL/beat. This scenario might be referred to as“fragmented flow” because the pump is taking on some of the flow, inthis case, most of the flow. By removing blood from the ventricle thepump operates to reduce loading on the ventricle and allow the ventricleto recover.

In some embodiments, the pump can pump blood through the impellerassembly 592 at flow rates of at least about 3.5 liters per minute(Lpm), at least about 4 Lpm, at least about 4.5 Lpm, at least about 5Lpm, etc. In some arrangements, the pump can pump blood through theimpeller assembly 592 at flow rates in a range of about 3.5 Lpm to about6 Lpm, or in a range of about 4 Lpm to about 5.5 Lpm. In somearrangements, the pump can pump blood through the impeller assembly 592at flow rates in a range of about 4.5 Lpm to about 5.5 Lpm. Additionaldetails of impellers 508 capable of pumping blood at these flow rates isdescribed in U.S. patent application Ser. No. 13/802,570, entitled“IMPELLER FOR CATHETER PUMP,” filed on Mar. 13, 2013, which isincorporated by reference herein in its entirety and for all purposes.

During operation of the impeller assembly 592, the impeller 508 canreduce the ventricular pressures considerably, which can improve patientoutcomes, as explained herein. For example, as shown in FIG. 20, duringoperation of the impeller 508 when the impeller assembly 592 is in aproper treatment location, the pressure P₂′ in the left ventricle 532may be reduced to less than about 6 mmHg, or less than about 5 mmHg.Such reductions in ventricular pressures are believed improve the healthoutcomes of patients who have suffered a myocardial infarction. Amongother potential benefits, a reduction in LV pressure may reduce pressureon the coronary arteries. This can increase perfusion to the through thecoronary arteries thereby improving clinical outcomes.

Furthermore, as with the aortic pressure P₁′ measured by the proximalsensor assembly 521, the ventricular pressure P₂′ may be relativelysmooth, exhibiting reduced pulsatility. In some arrangements, thepressure curve P₂′ (reflecting ventricular pressures when the impellerassembly 592 is in a proper treatment position) may exhibit lesspulsatility than the pressure curve P₁′ (reflecting aortic pressureswhen the impeller assembly 592 is in the proper treatment position).

Thus, the pressure curves P₁′ and P₂′ may represent baseline signaturesof the treatment procedure when the impeller assembly 592 is in acorrect or proper treatment position (e.g., FIG. 19). The methods andsystems disclosed herein can utilize the baseline signatures P₁′ and P₂′for determining the position of the impeller assembly 592 relative tothe heart 530.

For example, when the impeller assembly 592 is properly positioned, thedistal sensor assembly 524 can be positioned within the left ventricle532 and can detect fluid flow having a baseline signature similar tothat plotted in P₂′, which may correspond to a ventricular baselinesignature V. In addition, or alternatively, when the impeller assembly592 is properly positioned, the proximal sensor assembly 521 can bepositioned within the aorta 531, and can detect fluid flow having abaseline signature similar to that plotted in P₁′, which may correspondto an aortic baseline signature A. When the impeller assembly 592 isproperly positioned across the aortic valve 533, the processing unit 503can process the signals transmitted to the controller 502 by the sensorassemblies 521 and/or 524. For example, various pre-processingprocedures may be performed to convert the raw sensor data (e.g., anoptical signal representative of pressure) into data to be processed bythe processing unit 503. The pre-processing can include applying afilter to the signal. The pre-processing can be performed by theprocessor or a separate component. The processing unit 503 can associateventricular and/or aortic baseline signatures V, A with a properplacement configuration. Any suitable signal processing techniques inthe time domain and/or frequency domain (e.g., Fourier analysis) may beperformed on the baseline signatures A, V to characterize the signalsdetected by the sensor assemblies 521, 524 when the impeller assembly592 is positioned at a desirable or proper position and orientation. Thecontroller 502 can store the baseline signatures A, V in memory forcomparison with other signatures detected by the sensors and processedby the controller 502.

As explained above, it can be advantageous to ensure that the catheterpump is properly positioned and aligned (e.g., across the aortic valve533 in the exemplary embodiment) throughout the treatment procedure, sothat the pump provides adequate, consistent cardiac assistance to thepatient. The impeller assembly 592 may become misaligned in a variety ofways during a treatment procedure. For example, the proximal end of thecatheter body 504 may be disturbed by the patient, or other externalforces may cause the impeller assembly 592 to move within the heart 530.

In various embodiments, the impeller assembly 592 may be initiallyaligned in a proper treatment location, such as that shown in FIG. 19.The embodiments disclosed herein can monitor the position of theimpeller assembly 592 to ensure that the impeller assembly 592 does notslide distally or proximally to an undesired position. For example, theembodiments disclosed herein can monitor the impeller assembly 592 toalert the clinician if the impeller assembly is moving from a propertarget position (such as that shown in FIG. 19) towards an improperposition. During operation of the catheter assembly 500, it may beundesirable for the inlets 523 or the outlets 522 to be disposedproximate the aortic valve 533. For example, when the impeller assembly592 is misaligned, the catheter assembly 500 may not provide adequatecardiac assistance to the patient. Furthermore, misalignment of theimpeller assembly 592 may also damage the patient's anatomy or poseother risks. For example, portions of the aortic valve 533 or the wallsof the vasculature may be sucked into the inlets 523 or outlets 522,which can damage the patient and lead to negative patient outcomes.Misalignment can also increase the risk of thrombus and stroke.

When the impeller assembly 592 is misaligned, various embodimentsdisclosed herein can detect such misalignment using the proximal sensorassembly 521 and/or the distal sensor assembly 524. Disturbancesignatures, which may be determined based on plots of pressure detectedby the proximal and/or distal sensor assemblies, may comprise asignature representative of a configuration in which the impellerassembly 592 is misaligned relative to a proper orientation or position.

For example, a disturbance signature V′ (not shown) detected by thedistal sensor assembly 524 may represent a misaligned configuration inwhich the inlets 523 are proximal and/or near the aortic valve 533.Without being limited by theory, if the inlets 523 are disposedproximal, over, near, and/or aligned with the aortic valve 533, thepressure signature V′ detected by the distal sensor assembly 524 andprocessed by the controller 502 may be substantially different from thebaseline pressure signature V when the impeller assembly 592 is properlypositioned in the anatomy. For example, the disturbance pressuresignature V′ may be at different absolute pressures than the baselinepressure signature V when the inlets 523 and the distal sensor assembly524 are positioned fully within the left ventricle 532. Furthermore, thedisturbance pressure signature V′ may exhibit different pulsatilityand/or pressure spikes than the baseline pressure signature V. Apressure difference ΔP^(V′) of the disturbance signature V′ betweenminimum and maximum pressures may also be different from the pressuredifference ΔP^(V) of the baseline signature V. The disturbance signatureV′ may also be substantially different from the baseline signature Vover time. For example, the disturbance signature V′ may have a periodor wavelength that is sufficiently different from the wavelength of thebaseline signature V so as to indicate that the inlets 523 are near theaortic valve 533. In some cases, there may also be a time lead or lagbetween the disturbance and baseline signatures.

Similarly, an aortic disturbance signature A′ detected by the proximalsensor assembly 521 may represent a misaligned configuration in whichthe outlets 522 are near and/or distal the aortic valve 533. If theoutlets 522 are disposed distal, over, near, and/or aligned with theaortic valve 533, the disturbance pressure signature A′ detected by theproximal sensor assembly 521 and processed by the controller 502 may besubstantially different from the baseline pressure signature A when theimpeller assembly 592 is properly positioned in the anatomy, e.g.,within the aorta 531. Furthermore, in some cases, the pulsatility of theaortic disturbance signature A′ may be different as compared with thebaseline signature A. As with the ventricular disturbance signature V′,there may be other substantial differences relative to the aorticbaseline signature A.

The impeller assembly 592 can be misaligned in other ways. For example,in some situations, the entire impeller assembly 592 may be positionedcompletely within the left ventricle 532. In such situations, bloodflowing through the outlets 522 may be occluded by the valve 533, suchthat the flow rate through the aorta 531 and vascular system is notappreciably increased relative to the normal cardiac output of thepatient's heart. In such arrangements, the measurements detected by theproximal sensor assembly 521 and the distal sensor assembly 524 may beabout the same (i.e. the difference is negligible), which would indicatethe assembly 592 is entirely in the left ventricle 532 or aorta 531,depending on the pressure reading. In one example, if the differentialbetween the proximal and distal sensors begins to rapidly approach zero,the processor identify imminent misplacement in either the aorta orventricle.

Turning to FIGS. 21A-21D, another embodiment is disclosed. FIG. 21A is aschematic side view of an impeller assembly 592 as the clinicianadvances it through the patient proximal the aortic valve 533. FIG. 21Bis a schematic side view of the impeller assembly 592 as the impellerassembly 592 reaches a proper, target location across the aortic valve533. FIG. 21C is a schematic side view of the impeller assembly 592showing the impeller assembly as fully disposed in the left ventricle532, e.g., in a situation in which the clinician overshoots the targetposition. In the embodiment of FIGS. 21A-21C, the impeller 508 isinactive (e.g., not rotating) as the clinician advances the impellerassembly 592 through the vasculature. In such embodiments, the distalsensor assembly 524 can monitor the location of the impeller assembly592 as the impeller assembly 592 approaches the target position. Thedistal sensor assembly 524 can also determine whether the impellerassembly 592 overshoots the target position (e.g., FIG. 21C).

FIG. 21D is a theoretical plot of pressure over time measured by thedistal sensor assembly at the positions illustrated in FIGS. 21A-21B,when the impeller is not rotating. The plots shown in FIG. 21D can beused to recognize when the pump is moving from the position of FIG. 21Ato the positions of FIGS. 21B-21C. When the pump is positioned as shownin FIG. 21A, the pressure curve may look like either curve A or curve Billustrated in FIG. 21D. The shape of the curve depends on whetherpulsatility can be detected. For example, if pulsatility is detected,the pressure detected by the distal sensor assembly 524 may appearsimilar to the plot in curve A. However, if little to no pulsatility isdetected by the distal pressure assembly 524, then the pressure mayappear similar to the plot in curve B. The overall level of pressure,however, would be relatively high in both curves A and B because thedistal sensor assembly 524 is influenced by the aortic pressure whenpositioned as shown in FIG. 21A. As the pump moves to the targetposition (e.g., the position shown in FIG. 21B) and/or the positionshown in FIG. 21C, the pressure may drop as mostly the ventricularpressure is detected by the distal sensor assembly 524. Thus, when inthe positions shown in FIGS. 21B-21C, the pressure curve may move fromcurve A or B to curve C, as shown in FIG. 21D. Moreover, as shown incurve C, the shape of the curve may smooth or flatten relative to curvesA or B. Thus, the algorithm can recognize that, if the pressure plotmoves from curve A or curve B to curve C as the clinician pushes thepump distally, the impeller housing 592 is moving from proximal theaortic valve towards the target position. The algorithm may also comparethe pressure plots to various history or expert data to determinewhether the impeller assembly 592 is in the proper target location(e.g., FIG. 21B) or if the impeller assembly 592 is disposed entirelywithin the left ventricle 532. Furthermore, if the system includes theproximal sensor assembly 521, then pressure data measured by bothsensors 521, 524 may be used to determine if the impeller assembly 592is positioned in the configuration of FIG. 21C.

FIG. 22A is a schematic side cross-sectional view of a heart 730 havinga region of myocardial infarction 734 along a wall of the left ventricle732. FIG. 22B is a schematic front cross-sectional view of the heart 730shown in FIG. 22A. When a patient has a heart attack, regions of theheart may comprise dead tissue, or an infarct 734. Edges of the infarctmay still be alive but ischemic; accordingly, it can be advantageous toprevent the infarct 734 from spreading to surrounding healthy hearttissue. Reducing the extension of the myocardial infarct 734 canconsiderably improve patient outcomes. One way to prevent the extensionof the infarct 734 is to reduce the pressure P₂ exerted against theventricular walls. For example, lowering the pressure P₂ can reduce theextent to which coronary arteries are squeezed, improving endocardialcirculation which promotes the flow of blood to the infarct 734. In thisway the infarct continues to receive blood and the extension of theinfarct may be curtailed. This may lead to dramatic improvements inacute outcomes and also reduce the number of myocardial infarctionpatients who present with chronic heart failure. As explained herein,various embodiments disclosed herein can prevent the infarct 734 fromspreading by an amount 6 to a larger region 735 shown in dashed lines inFIG. 22B. In some arrangements, for example, the impeller assembly 592can reduce the spread of the infarct 734 by an amount 6 in a range ofabout 3 mm to about 8 mm, e.g., about 5 mm. Even such small reductionsin the extension of the infarct 734 can dramatically improve patientoutcomes, because small reductions in the extension can result in largereductions of area of the infarct 734.

Various embodiments disclosed herein can advantageously reduce theaverage pressure in the left ventricle 732 by a significant amount,which can improve patient outcomes. In some embodiments, it can beadvantageous to initially provide sufficient support to the heart suchthat the heart and impeller assembly 592 pump at least about 2 Lpm(e.g., at least about 4 Lpm) to ensure sufficient organ perfusion evenif the heart is barely able to pump. As explained above, the impeller508 may be configured pump blood through the impeller assembly 592 atflow rates of at least about 2 liters per minute (Lpm), at least about2.5 Lpm, at least about 3.5 Lpm, at least about 4 Lpm, at least about4.5 Lpm, at least about 5 Lpm, etc. In some arrangements, the pump canpump blood through the impeller assembly 592 at flow rates in a range ofabout 2 Lpm to about 6 Lpm, or in a range of about 4 Lpm to about 5.5Lpm. In some arrangements, the pump can pump blood through the impellerassembly 592 at flow rates in a range of about 4.5 Lpm to about 5.5 Lpm.Additional details of impellers 508 capable of pumping blood at theseflow rates is described in U.S. patent application Ser. No. 13/802,570,entitled “IMPELLER FOR CATHETER PUMP,” filed on Mar. 13, 2013, which isincorporated by reference herein in its entirety and for all purposes.

Thus, in some embodiments, the clinician can insert the impellerassembly 592 to a desired treatment location (e.g., FIG. 19) and canactivate the impeller 508 at operational speeds. The impeller 508 canpump blood at a sufficient flow rate to ensure that blood adequatelyperfuses into the patient's organs to support the patient. The cliniciancan adjust the position of the impeller assembly 592 to achievedesirable pressure profiles in the left ventricle 732. For example, asexplained above, the distal sensor assembly can measure the pressure P₂within the left ventricle 732 during the treatment procedure. FIG. 22Cis a theoretical, exemplary plot of pressure P₂ over time in the leftventricle 732 of the heart 730 of FIGS. 22A-22B prior to activation ofthe impeller assembly 592. Thus, FIG. 22C illustrate a theoretical,example pressure P₂ that may be detected by distal sensor assembly 524before the pump is activated to support the heart. For example, in FIG.22C, the impeller 508 may not be activated (or may not be fully rampedto speed) such that the ventricular pressures are relatively high. Asshown in FIG. 22C, for example, without support from the impeller 508,patients that have suffered a heart attack may have average ventricularpressures P₂ as high as 15 mmHg to about 20 mmHg, or higher pressures(such 30 mmHg). In some cases, patients who have suffered a heart attackmay have average ventricular pressures (e.g., left ventricularend-diastolic pressure, or LVEDP) that are about 25% to about 300%higher than normal average ventricular pressures, e.g., averageventricular pressures that are about 30% to about 100% higher thannormal average ventricular pressures. The extent of pressure increasesin the left ventricle for heart attack patients can vary, but typicallythe pressures in the left ventricle are significantly higher for heartattack patients than for normal human cardiac activity. Such highventricular pressures can squeeze the tissue in the walls of theventricle 732, which may cause the infarct 734 to spread.

In some embodiments, the clinician can move the impeller assembly 592relative to the aortic valve 533 until the impeller 508 providesadequate flow rate and reduced ventricular pressure. The motor speedthat drives the impeller 508 can also be adjusted by the clinician. Insome embodiments, the clinician can estimate how far the inlets 523 arepast the aortic valve 533. For example, to provide adequate flow and/orreduced ventricular pressures P₂, it may be desirable to place theinlets 523 between about 0.5 cm and about 4 cm distal the aortic valve533. In some embodiments, it can be advantageous to place the inlets 523in a range of about 1.5 cm to about 3 cm distal the aortic valve 533,e.g., about 2 cm distal the aortic valve 533 in one embodiment. Theclinician can use a mechanical marker at the proximal end of thecatheter body outside the patient's body to provide a rough estimate ofthe position of the impeller assembly 592 relative to the aortic valve533. The clinician can manipulate the impeller assembly 592 until thepressures detected by the distal sensor assembly 724 are at suitably lowaverage levels.

FIG. 22D represents a theoretical, example pressure profile afterproviding a coarse adjustment of the impeller housing 592 relative tothe aortic valve 533. For example, the clinician can estimate a distanceof about 2 cm below the aortic valve 533 (using, for example, hash markson the catheter body or other techniques), and can place the inlets 523and distal sensor assembly 524 near that location. When the impeller 508is at operational speeds and the inlets 523 are appropriatelypositioned, the impeller assembly 592 can pump blood at flow ratessufficient to perfuse organs (e.g., at least about 4 Lpm) while alsosignificantly reducing the pressure in the left ventricle 732. Forexample, as shown in FIG. 22D, the average ventricular pressure P₂ canbe reduced to less than about 15 mmHg, less than about 10 mmHg, lessthan about 6 mmHg, or more particularly, less than about 5 mmHg. In someembodiments, the ventricular pressure P₂ can be reduced to be in a rangeof about 2 mmHg to about 15 mmHg, about 3 mmHg to about 10 mmHg, about 4mmHg to about 8 mmHg, about 4 mmHg to about 6 mmHg, about 4 mmHg toabout 5 mmHg, etc. In some embodiments, the average ventricular pressurefor heart attack patients can be reduced to a level that is less thanabout 135% of the normal average ventricular pressure (e.g., normalaverage pressure for humans that have normal cardiac health), less thanabout 130% of the normal average ventricular pressure, less than about125% of the normal average ventricular pressure, less than about 120% ofthe normal average ventricular pressure, less than about 115% of thenormal average ventricular pressure, less than about 110% of the normalaverage ventricular pressure, or less than about 105% of the normalaverage ventricular pressure. By reducing the ventricular pressure tosuch low ranges, the extension of the myocardial infarct 734 can bereduced, which can result in considerable improvement for patientoutcomes. In other embodiments, the peak ventricular pressure (e.g., themaximum pressure) can be reduced to less than about 6 mmHg, or moreparticularly, less than about 5 mmHG. In some embodiments, the peakventricular pressure can be reduced to be in a range of about 2 mmHg toabout 8 mmHg, about 3 mmHG to about 6 mmHg, about 4 mmHg to about 5mmHg, etc. The peak ventricular pressure can be reduced to be less thanabout 135% of the normal peak ventricular pressure (e.g., normal peak ormaximum pressure for humans that have normal cardiac health), less thanabout 130% of the normal peak ventricular pressure, less than about 125%of the normal peak ventricular pressure, less than about 120% of thenormal peak ventricular pressure, less than about 115% of the normalpeak ventricular pressure, less than about 110% of the normal peakventricular pressure, or less than about 105% of the normal peakventricular pressure.

Once the pump is roughly positioned such that it maintains a sufficientflow rate to ensure adequate organ perfusion, in various embodimentsdisclosed herein, the clinician can optimize positioning by movingimpeller assembly 592 to reduce pressure spikes and smooth out thepressure profile P₂. As shown in FIG. 22D, even though the value of thepressure P₂ is relatively low, there are numerous pressure spikes, whichmay damage the ventricle walls and permit the infarct 734 to spread. Theclinician can view the pressure plot P₂ on a user interface and canadjust the pump to reduce the spikes and/or smooth out the pressurecurve P₂ in real-time. For example, the clinician can move the impellerassembly 592 proximally or distally (and may also adjust the motorspeed) until the pressure curve P₂ becomes relatively smooth and flat,e.g., which may correspond to of the pressure plot shown in FIG. 22E.The smooth curve P₂ at low pressures in the ventricle 732 cansignificantly improve patient outcomes. In some embodiments, a processoror controller (such as the processing units disclosed herein) canprocess the detected pressures and can indicate on the user interfacewhether the measured pressures are acceptably low in the left ventricle.

The pump disclosed herein can also reduce remodeling of the leftventricle 732. After heart attacks or other cardiac events, the leftventricle 732 may gradually become remodeled, which may lead tolong-term heart problems, such as chronic heart failure (e.g. dilatedcardiomyopathy). Advantageously, the pump disclosed herein may reducethe extent of ventricular remodeling when operated at a proper treatmentposition over time. For example, using the impeller assembly 592disclosed herein even for several hours may have positive effects onremodeling. Use of the pump for longer periods (e.g. days, weeks, oreven months), may dramatically reduce or prevent remodeling. In someembodiments, operating the impeller assembly 592 at pressure profilessuch as that shown in FIG. 22E for a duration of between about 1 hourand 10 hours, or between about 5 hours and 10 hours, may reduceremodeling. In some embodiments, the pump can be used for even longerperiods of time, such as over a period of several days. Thus, using thepump at sufficient flow rates and low pressures can reduce the degree ofventricular remodeling after a heart attack.

Accordingly, in the embodiment described herein with respect to FIGS.22A-22E, the impeller assembly 592, when properly positioned, canadvantageously provide sufficient support to the heart to maintain flowrates high enough to adequately perfuse the organs of a patient. Inaddition, the impeller assembly 592 can significantly reduce thepressures in the left ventricle, which can dramatically reduce theextension of a myocardial infarct, significantly improving patientoutcomes. Moreover, the impeller assembly 592 can also reduce the extentof ventricular remodeling after a heart attack, reducing the risk ofchronic heart failure.

FIG. 23A is a flowchart illustrating a computer-implemented method 600for determining a position of a cannula relative to an anatomy of apatient. As explained herein, the method can be encoded in varioussoftware modules, which can be implemented on the processing unit 503.The method can be implemented in software, firmware, and/or hardware.The method 600 can begin in a block 601 to receive a signal from asensor disposed near a proximal port of the cannula. The sensor can beany suitable sensor configured to measure a property and/orcharacteristic of the fluid passing through the cannula. In someembodiments, the sensor is a pressure sensor, e.g., an optical pressuresensor. The proximal port can comprise a fluid outlet, and the sensorcan measure fluid properties of blood flowing through the fluid outlet.In some embodiments, a distal sensor can be disposed near a distal portof the cannula, which may act as a fluid inlet in some arrangements. Thedistal sensor can be any suitable sensor, such as a pressure sensor. Thedistal sensor can measure fluid properties of blood flowing through theinlets.

In a block 602, the signal can be processed to determine a fluidsignature related to a property of the fluid flowing through theproximal port. For example, the raw signal from the sensor can bepre-processed to convert the detected signal (e.g., an optical signal, avoltage, a current, etc.) into a parameter data representative of fluidflow. A processor can filter the raw signal to extract the parameterdata, e.g., pressure values. The parameter data can comprise data thatcan be manipulated by a processor. The processor can detect a signatureof the parameter data. For example, the processor can determine theshape of the pressure waveform over time, including, e.g., first andsecond derivatives of the pressure data and other operations that may beused to identify a signature of the flow. In some embodiments, thesignal can comprise a pressure signal (e.g., an optical signalrepresentative of the sensed pressure), and the signature can representthe pressure of the fluid flowing through the proximal port. Similarly,in arrangements having a distal port and a distal sensor, the raw signalfrom the distal sensor can be processed into a distal signature.

Turning to a block 603, the determined fluid signature can be comparedwith a baseline signature. The baseline signature can be associated witha proper position of the cannula during a treatment procedure. Forexample, as explained herein with respect to left-side supportprocedures, it may be desirable to position the cannula within thepatient such that the aortic valve is disposed between the inlets andoutlets of the cannula. Accordingly, in a proper positioning of thecannula during the procedure, the proximal port can be disposed proximalthe aortic valve. In embodiments with a distal port and distal sensor,the distal port can be disposed distal the aortic valve relative to thecannula. The baseline signature can be representative of the pressure(or other fluid property) of the blood flowing through the inlets andoutlets when the cannula is properly positioned.

In a block 604, the position of the cannula can be determined based atleast in part on the comparison of the determined fluid signature withthe baseline signature. In some embodiments, if the determined fluidsignature (e.g., a disturbance signature) is significantly differentfrom the baseline signature, the method 600 can determine that thecannula is in an improper position during the procedure. In a block 605,the determination or result can be displayed to the clinician, e.g. tonotify the clinician whether or not the impeller housing is in a propertreatment position. For example, a user interface can notify theclinician that the impeller assembly is in an improper position, and theclinician can reposition the cannula accordingly.

In some arrangements, the method 600 can compute a difference between amean baseline signature and a mean disturbance signature. If thecomputed difference exceeds a predetermined threshold, then it can bedetermined that the cannula is misaligned. In some arrangements, themethod 600 can compare pressure differences ΔP associated with thedifference between minimum and maximum pressures, P_(min) and P_(max),respectively, between the baseline signature and the determinedsignature. If the compared pressure differences ΔP are substantiallydifferent, then the method 600 can determine that the cannula ismisaligned. In various embodiments, substantially different meansgreater than 5%, greater than 10%, greater than 25%, or greater than50%. In various embodiments, substantially different means greater than100%, greater than 150%, greater than 200%, greater than 250%, orgreater than 300%. In some arrangements, the period or wavelength λ ofthe determined signature can be compared with the period or wavelength λof the baseline signature. If the wavelength λ of the determinedsignature differs substantially from the wavelength λ of the baselinesignature, then the method 600 may determine that the cannula ismisaligned. It should be appreciated that other metrics may be used todetermine whether or not the cannula is misaligned relative to theanatomy. Indeed, any suitable time-domain and/or frequency domain signalprocessing methods, look-up tables, or other techniques may be used todetermine the position of the cannula relative to the anatomy.

Advantageously, in some embodiments, the method 600 can determinewhether the outlets 522 or inlets 523 of the cannula are near and/orsubstantially aligned with a cardiac valve, such as the aortic valve533. Such a determination may indicate, for example, that the cannula508 is sliding distally (in the case of the outlets 522 approaching thevalve 533) or proximally (in the case of the inlets 523 approaching thevalve 533). For example, although the cannula 508 may be initiallypositioned properly such that the valve 533 is between the inlets 522and outlets 523, the cannula 508 may slide distally due to some externaldisturbance. So long as the proximal sensor assembly 521 remains in theaorta 531, the controller 502 can process the signal detected by thesensor tip and may determine that the processed or determined signatureA′ (e.g., representative of pressure in the aorta 531) is substantiallysimilar to the baseline aortic signature A. In such a case, thecontroller 502 may indicate that the cannula 508 is properly positioned,even though the cannula 508 may have moved distally by a small amount.

However, if the cannula 508 continues to slide distally, e.g., towardsthe left ventricle 532, then the outlets 522 and the proximal sensorassembly 521 may approach the aortic valve 533 such that the outlets 522and proximal sensor assembly 521 are brought into close proximity to(and/or are substantially aligned with) the aortic valve 533. The signalreceived from the proximal sensor assembly 521 may be processed by thecontroller 502 to determine a signature of the flow through the outlets522. When the outlets 522 overlie or are sufficiently close to theaortic valve 533, the controller 502 may determine that the determinedsignature A′ is substantially different from the baseline aorticsignature A. The controller 502 may therefore indicate that the cannula508 is misaligned. Furthermore, based on known or estimated flowsignatures when the outlets 522 overlie the aortic valve 533, thecontroller 502 may recognize that the outlets 522 overlie, align with,and/or are in close proximity with the aortic valve 533. The controller502 may communicate with the user interface 505, which can inform theclinician that the cannula 508 is sliding distally and that theclinician should reposition the cannula 508. Although the example abovediscussed the situation of the cannula 508 sliding distally, it shouldbe appreciated that similar methods may be conducted in situations inwhich the cannula 508 slides proximally such that the inlets 523approach and come in close proximity to (and/or overlie) the aorticvalve 533. Accordingly, in addition to determining whether or not theaortic valve 533 is disposed between the inlets 523 and outlets 522, theembodiments disclosed herein can also determine whether or not theinlets 523 and/or outlets 522 are in close proximity to and/or overlyingthe aortic valve 533 (or another cardiac valve).

FIG. 23B is a schematic of an exemplary system architecture forimplementing the techniques described herein. The system includes aprocessor 610 configured to process signals received from one or moresensor assemblies 621, 624. For example, a proximal sensor assembly 621and/or a distal sensor assembly 624 may transduce information relatingto a flow condition in the impeller assembly, such as pressure. In someembodiments, for example, the sensor assembly 621, 624 can opticallydetect the pressure at a proximal or distal sensor location. Theprocessor 610 can include a filter 613 and/or other components, e.g., ananalog-to-digital converter (ADC) to filter the raw data and convert themeasured signals into pressure data that represents the pressure in theanatomy.

The processor 610 can also receive additional inputs, such asinformation 611 from adjunctive devices such as a heart rate monitor,ECG or EEG, blood glucose monitor, pulmonary catheter (for measuringpulmonary capillary wedge pressure), or an accelerometer. The adjunctivedevices can provide the processor 610 with additional information 611 tohelp inform decisions made by the processor 610 during treatment. Inaddition, expert data 612 can be received and processed by the processor610. Expert data 612 can comprise any suitable data that can inform theclinician about the status of the catheter pump. For example, expertdata 612 can inform the clinician about whether or not the pump isfunctioning properly, blockage in the pump, etc.

The processor 610 can include a comparator 614 configured to compare andotherwise manipulate multiple values relative to one another, e.g.,based on a comparison of voltages and/or currents. For example, thecomparator 614 can evaluate stored baselines 615 and signatures 616(which may be stored in a look-up table 617, for example) to determinewhether the impeller assembly is aligned or misaligned, in accordancewith the embodiments described herein. The processor 610 can beprogrammed to decide whether or not the impeller assembly is aligned,and can notify the clinician by way of a user interface 618. Theclinician can monitor the pressures displayed on the user interface 618in real-time and can adjust the impeller assembly 592 to achieve adesired pressure profile.

Although the embodiments illustrated with respect to FIGS. 19-23B aredescribed with respect to a left-side assist procedure, it should beappreciated that the embodiments disclosed herein can similarly be usedin other procedures. For example, in other procedures, a distal portionof a cannula can be positioned in one part of the anatomy having a firstbaseline pressure signature and a proximal portion of the cannula can bepositioned in another part of the anatomy having a second baselinepressure signature. If the proximal and/or distal portions becomemisaligned from a desired orientation, the controller can detectrespective disturbance signatures indicating such misalignment.

Furthermore, it should be appreciated that the methods and systemsdisclosed herein can continuously monitor the position and movement ofthe impeller assembly 592 throughout a treatment procedure. If thecannula 508 of the impeller assembly 592 moves relative to the anatomy,the embodiments disclosed herein can track in real-time the position ofthe cannula 508 and can notify the clinician if misalignment of thecannula 508 is imminent. In addition, although the embodiments disclosedherein may relate to position detection of the impeller assembly 592using pressure sensors, it should be appreciated that the sensorassemblies can be used to measure other properties, such as flow rate,biological or chemical composition, temperature, etc.

C. Examples of Proximal Sensor Assemblies

FIG. 24 is a schematic perspective view of a catheter assembly 500having a proximal sensor assembly 521 disposed near an outlet 522 at aproximal portion of a cannula 508. Reference numerals used in FIG. 24may refer to similarly-numbered components in FIG. 18B. For example, thecatheter assembly 500 can include a catheter body 504, a cannula 508,and an impeller 512 disposed in the cannula 508. The cannula 508 can becoupled with a distal end portion of the catheter body 504 using anysuitable mechanism. For example, as shown in FIG. 24, a tubular portion516 of the cannula 508 can couple to the catheter body 504 by way of aferrule 536, as explained above with respect to FIGS. 11-15.

In the embodiment of FIG. 24, the proximal sensor assembly 521 can bedisposed at the first proximal sensor location 521A, which can bepositioned near the outlets 522 (e.g., substantially axially alignedwith the outlets 522 in some arrangements). By disposing the proximalsensor assembly 521 close to the outlets 522 (e.g., substantiallyaligned relative to the outlets 522 along the axis of the catheterpump), assembly 521 can obtain accurate measurements of various fluidproperties of blood that flows through the outlets 522, such as thepressure of fluid flowing through the outlets 522.

The proximal sensor assembly 521 can include a sensor tip 542 and anelongate connector 541 providing data communication between the sensortip 542 and the controller 502 (shown in FIG. 18A). In some embodiments,the proximal sensor assembly 521 can comprise a pressure sensorassembly, such as an optical fiber sensor. Advantageously, fiber opticsensors accurately measure pressure because such optical sensors may bemore sensitive to slight pressure variations than other types ofpressure sensors (such as MEMS-based pressure sensors or other types ofsensors). An example of a suitable sensor assembly 521 is the FOP-M260fiber optic pressure transducer, manufactured by FISO Technologies Inc.,of Quebec, Canada. In other arrangements, any other suitable type ofsensor can be used.

The sensor tip 542 can be disposed proximate a proximal window 537formed through an outer surface of the catheter assembly 500 (e.g., thesensor tip 542 can be substantially axially aligned with the window537). For example, as shown in FIG. 24, the window 537 can be formedthrough a tube or sleeve of the cannula 508 disposed about the bearinghousing. In some embodiments, the window 537 can be formed through anouter surface of the elongate catheter body 504, or through an outersurface of a connector or other structure disposed between the catheterbody 504 and the impeller 512. In some embodiments, the window 537 canbe formed through a proximal portion of the impeller 512, e.g., formedthrough an outer surface of an impeller hub. The window 537 can providefluid communication between the sensor tip 542 and the blood flowingthrough the outlets 522, so that the sensor tip 542 can detectproperties of the blood, e.g., the localized blood pressure. Forexample, the window 537 and the proximal sensor tip 542 can be disposedalong and/or near an outer surface of a tubular body of the catheterassembly 500 near the outlets 522. The window 537 can be substantiallyaligned with the outlets 522 of the pump. Furthermore, as explainedabove, the elongate body 96 of the sheath assembly 88 can be movedrelative to the sensor assembly 521 and/or the impeller 512 to exposethe window 537 and/or the sensor tip 542. For example, the clinician canslide the elongate body 96 proximally such that a distal-most end of theelongate body 96 exposes the window 537 and/or the sensor tip 542.Moving the elongate body 96 proximally can also cause the cannula and/orimpeller 512 to expand to deployed configurations.

FIG. 25 is a side cross-sectional view of the catheter assembly 500 ofFIG. 24. As with the catheter assembly of FIG. 10, the catheter assembly500 of FIG. 24 can include a bearing housing 546 (which may be similarto the bearing housing 146A of FIG. 10), a thrust bearing 547 (which maybe similar to the thrust bearing 204 of FIG. 10), a thrust bearing brace548 (which may be similar to the thrust bearing brace 208 of FIG. 10), acoupler 549 (which may be similar to the coupler 200 of FIG. 10), and animpeller shaft 538 attached to the impeller 512. As shown in FIG. 25,the elongate connector 541 can pass along the length of the catheterassembly 500, and the sensor tip 542 can emerge at the window 537 nearthe outlets 522.

FIG. 26 is a front end, cross-sectional view of the elongate catheterbody 504. As with the embodiment illustrated in FIG. 9, the catheterbody 504 can include a central lumen 540A for receiving the drive shaftof the catheter pump (e.g., similar to drive shaft 144 disclosed above).The catheter body 504 can also include a second, infusate lumen 540Bconfigured to supply infusate (such as saline) to a distal end near theimpeller assembly 512. As with the embodiment of FIG. 9, the catheterbody 504 can include a third, pull-wire lumen 540C configured to receivepull wires for enhancing the connection between the catheter body 504and the bearing housing 546. To accommodate the elongate connector 541of the proximal sensor assembly 521, the elongate catheter body 504 canalso comprise a proximal sensor lumen 540D. Thus, the elongate connector541 can extend from near a proximal end of the catheter body 504 throughthe proximal sensor lumen 540 to a distal portion of the catheter body504. As shown in FIG. 26, the sensor lumen 540D can be disposed oppositethe pull-wire lumen 540C (e.g., by about 180°), and the infusate lumen540B can be disposed between the sensor lumen 540D and the pull-wirelumen 540C (e.g., by about 90° relative to the other lumens 540C, 540D).In other embodiments, the sensor lumen 540D and the infusate lumen 540Bcan be disposed directly opposite one another, e.g., separated by about180°. Advantageously, separating the lumens 540B-540D from one anotherby a maximum amount can prevent accidental fluidic shorting between thelumens.

FIG. 27 is a schematic perspective view of the bearing housing 546 shownin FIG. 25. The bearing housing 546 can include a trough 539 formed inan outer surface of the bearing housing 546. The trough 539 can be sizedand shaped to receive the connector 541 and/or sensor tip 542 of theproximal sensor assembly 521. Thus, the connector 541 and the sensor tip542 can pass from the sensor lumen 540D through the trough 539 betweenthe bearing housing 546 and an outer sleeve surrounding the bearinghousing 546, e.g., the tubular portion 516 of the cannula 508. Thetrough 539 can be formed in any suitable manner, for example, bymachining.

The elongate connector 541 of the proximal sensor assembly 521 canextend proximally to the proximal end portion of the catheter body 504.The connector 541 (e.g., an optical fiber cable) can pass through anaperture or opening formed through the outer surface of the catheterbody 504 at the proximal end portion. In other arrangements, theconnector 521 can extend laterally through a motor housing or flowdiverter at a proximal end of the assembly 500 outside the patient.

Accordingly, in some embodiments, a proximal sensor assembly 521 canextend from outside the patient to a proximal portion of the cannula 508near the outlets 522 (e.g., substantially axially aligned with theoutlets 522 in some arrangements). The assembly 521 can comprise apressure sensor, which can comprise a fiber optic pressure sensor. Itshould be appreciated that such fiber optic sensors may be delicate. Forexample, fiber optic sensors may be easily damaged and/or broken duringoperation or manipulation of the catheter pump, or during insertion ofthe sensor assembly 521. Typically the failure mode is by bending orcutting. Accordingly, it can be important to provide sufficientprotection to the sensor assembly (including the sensor tip 542 andconnector 541) to prevent damage to the optical fiber. Advantageously,the embodiments disclosed herein enable the use of fiber optic sensors,because the sensor pathways are sufficiently sized to allow for passageof the optical fibers without imparting excessive stresses on thefibers. Any stresses experienced by the fiber are tensive, and suchfibers are generally resilient when exposed to tensile forces as opposedto bending. For example, the use of a sensor lumen in the catheter body504 and a trough 539 in the bearing housing 546 can accommodate the useof relatively delicate optical fibers. The relatively smooth transitionbetween the catheter body 504 and the cannula 508, in addition to thecareful routing of the connector 541, may at least in part act toprotect optical fiber pressure sensors from abrasion, rubbing, andkinking. In turn, using optical fibers to measure pressure at theoutlets 522 can improve the accuracy of pressure measurements.

D. Examples of Distal Sensor Assemblies

FIG. 28 is an image of a cannula 508 having a distal sensor assembly 524at the first distal sensor location 524A shown in FIG. 18B, according toone embodiment. The distal sensor assembly 524 can include a sensor tip542 (shown schematically in the image of FIG. 28) and an elongateconnector 541 extending proximally from the first distal sensor location524A to the proximal end of the catheter assembly 500. The cannula 508can include a plurality of circumferential rings 551 that provide radialstiffness to the cannula 508. An elastic coating 552 can be applied overthe rings 551 to form a flow duct through which blood can flow.

The distal sensor assembly 524 shown in FIG. 28 comprises a fiber opticpressure sensor. In particular, the distal sensor assembly 524 shown inFIG. 28 comprises the FOP-M260 fiber optic pressure transducer,manufactured by FISO Technologies Inc., of Quebec, Canada. In otherarrangements, any other suitable type of sensor can be used. Asexplained above with respect to the proximal sensor assembly 521,optical fiber sensors can provide more accurate pressure readings thanother types of sensors. However, due to the delicate nature of theoptical fibers, it can be challenging to incorporate optical fibersensors into catheter assemblies because catheter assemblies typicallytraverse through a tortuous vascular system and include features thatmay damage the fibers (e.g. valve leaflets and the aortic arch).Likewise, catheter assemblies typically involve components which riskdamaging the optical fiber like edges and corners. It can be especiallychallenging to incorporate optical fiber sensors into the exemplaryapplication because the cannula is expandable and collapsible andsubjected to constant, strong forces from the aortic valve duringcontinued use.

In the embodiment of FIG. 28, the connector 541 and tip 542 are embeddedin or on an outer wall 553 of the cannula 508. For example, in someembodiments, the connector 541 and tip 542 can be encapsulated in thepolymer or elastic coating 552 surrounding spiral pattern rings 551,which corresponds to the circumference of the cannula 508. In theembodiment shown in FIG. 28, the connector 541 and tip 542 of the fiberoptic sensor can be coated with the rings 551 when the elastic coating552 is applied over the rings 551. As shown in FIG. 28, the fiberconnector 541 can be inserted under the rings 551 of the cannula 508,and the elastic coating 552 can be applied over both the rings 551 andthe sensor assembly 524. The coating 552 can be applied over theconnector 541 such that at least some slack remains in the connector541. By maintaining slack in the connector 541, the integrity of thesensor assembly 521 can be maintained, e.g., the connector 541 may beprotected from rupture when the rings 551 move. As with the proximalsensor assembly, the elongate body 96 of the outer sheath assembly 88may be moved relative to the distal assembly 524 to expose the sensingportion of the sensor assembly 524 to blood. For example, as explainedabove, the clinician can slide the elongate body 96 proximally to exposethe tip 542 to blood.

Coating the sensor assembly 524 in or on the cannula wall 553 canprovide one effective way to position the distal sensor assembly 524near the inlets 523 of the cannula 508. However, in some arrangements,disposing the connector 541 adjacent the rings 551 may damage theoptical fiber. Furthermore, during the coating process, it may bedifficult to ensure that the optical fiber is evenly and flatly appliedagainst the outer wall 553 of the cannula 508, which can result in a gapbetween the fiber and the rings 551.

Accordingly, in another embodiment, a protective tube 554 can bedisposed about the outer wall 553 of the cannula 508 to provideadditional protection for the optical fiber. For example, FIG. 29 is animage of a cannula 508 having a distal sensor assembly 524 at the firstdistal sensor location 524A shown in FIG. 18B, according to anotherembodiment. The protective tube 554 can be adhered, coated, or otherwiseattached to the outer wall 553 of the cannula 508. As shown in FIG. 29,the protective tube 554 can pass around the circumference of the wall553 in a spiral pattern. The protective tube 554 can be any suitabletubing, such as Pebax® 72D, 0.019″×0.027″ tubing.

The elongate connector 541 (e.g., the optical fiber, not shown in FIG.29) may be disposed through and along the protective tube 554 before orafter deploying the cannula 508 from the stored configuration to theexpanded configuration. For example, in one embodiment, the cannula 508and protective tube 554 are inserted into the heart 530 in the storedconfiguration and are expanded into the expanded configuration prior tothe activating the impeller 512. The distal sensor assembly 524 can beinserted through the protective tube 554 once the cannula 508 isexpanded to prevent damage to the fiber during deployment. In otherembodiments, the fiber can be disposed within the protective tube 554during deployment of the cannula 508 from the stored configuration tothe expanded configuration. The distal sensor assembly 524 can beadvanced through the protective tube 554, and the tip 542 (not shown inFIG. 29) can extend through a distal opening of the tube 554 at asuitable sensor location, such as the first distal sensor location 524Ashown in FIG. 29. The configuration of FIG. 29 can further protect theoptical fiber by using the protective tube 554 to shield the fiber fromexternal forces and stresses. Furthermore, in the embodiments of FIGS.28 and 29, the tip 542 can act to protect the sensor assembly 524, bypreventing the sensor from being sucked against the ventricle wall. Asabove, the clinician can slide the elongate body 96 of the sheathassembly 88 proximally to expose the tip 542 to blood.

FIG. 30 is a schematic side cross-sectional view of a cannula 508 havinga distal sensor assembly 524 at the second distal sensor location 524Bshown in FIG. 18B, according to one embodiment. As with FIG. 18B, in theembodiment of FIG. 30, a distal lumen 525 can pass distal the impeller512. The distal lumen 525 can pass at least partially through a tipmember 526, and can provide access to the distal portion of the catheterassembly 500. As shown in FIG. 30, the distal lumen 525 can besubstantially radially centered relative to the cannula 508. In otherembodiments, the distal lumen may be radially offset relative to thecannula 508. As shown in FIG. 30, the connector 541 and sensor tip 542may pass through the distal lumen 525. The sensor tip 542 can bedisposed adjacent a distal window 555 formed through the distal lumen525. The distal window 555 can provide fluid communication between thesensor tip 542 and blood flowing into the inlet 523 of the cannula 508.The sensor tip 542 can measure a suitable fluid property, such aspressure.

In some embodiments, the distal sensor assembly 524 can be insertedthrough the distal lumen 525 after deployment of the cannula 508 withinthe heart 530. In other embodiments, the sensor assembly 524 can bedisposed through the distal lumen 525 during deployment of the cannula508. Advantageously, the embodiment disclosed in FIG. 30 can act toprotect delicate sensors, such as fiber optic sensors, by disposing themwithin a protective lumen 525. Furthermore, centering the sensorassembly 524 relative to the outlets 523 may result in improved pressuredetection in some arrangements, because the sensor may detect localpressure fluctuations if disposed at the wall 553 of the cannula 508.Although a single distal window 555 is illustrated in FIG. 30, it shouldbe appreciated that additional windows may be formed through the distallumen 525 to provide sensor readings at multiple locations along thelumen 525.

Moreover, as shown in FIGS. 18B and 30, the tip member 526 can include adistal opening 527 passing therethrough. In some embodiments, the thirddistal sensor location 524C may be disposed at or near the distalopening 527 to provide sensor measurements at the distal-most positionof the catheter assembly 500. For example, in such arrangements, thedistal sensor assembly 524 can pass through the tip member 26, and thesensor tip 542 can be positioned at or near the distal opening 527. Insuch arrangements, the sensor tip 542 can measure properties, such aspressure, in the left ventricle at the third sensor location 524C. Asexplained above, the clinician can provide relative motion between theelongate body 96 of the sheath assembly 88 to expose the sensor assembly524 to blood. For example, the clinician can move the body 96 proximallyto cause the impeller and cannula to expand and to expose the sensor tip542 to blood.

In the embodiment of FIG. 30, the distal lumen 525 can extend proximallyto a proximal portion of the catheter assembly 500. The distal lumen 525can emerge from the proximal portion at any suitable location, such asan aperture formed in the catheter body 504, or through a back end of anexternal motor or drive assembly. In addition, as explained above, thetip 542 can act to protect the distal sensor assembly 524, by preventingthe sensor from being sucked against the ventricle wall and damaging thesensor.

Although the inventions herein have been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent inventions. It is therefore to be understood that numerousmodifications can be made to the illustrative embodiments and that otherarrangements can be devised without departing from the spirit and scopeof the present inventions as defined by the appended claims. Thus, it isintended that the present application cover the modifications andvariations of these embodiments and their equivalents.

What is claimed is:
 1. A catheter assembly comprising: a catheter body;a cannula coupled to a distal portion of the catheter body, the cannulahaving a proximal port and a distal port to enable a flow of bloodthrough the cannula from the distal port to the proximal port; animpeller disposed in the cannula between the proximal port and thedistal port and configured to generate the flow of blood through thecannula; a sensor assembly configured to measure a fluid property of theflow of blood through the cannula, wherein the sensor assembly comprisesan elongate connector and at least one of: (a) a proximal sensor coupledwith the catheter body and having a distal portion near the proximalport, and (b) a distal sensor coupled with the cannula and having adistal portion near the distal port, the catheter body configured toreceive the elongate connector through a sensor lumen from outside apatient to a location near the proximal port; and a bearing housingdisposed within the cannula, the bearing housing comprising a troughsized and shaped to receive the elongate connector between the bearinghousing and the cannula.
 2. The catheter assembly of claim 1, whereinthe sensor assembly comprises the distal sensor.
 3. The catheterassembly of claim 1, wherein the sensor assembly comprises a pressuresensor configured to measure a pressure of the flow of blood through thecannula and generate a signal related to the pressure.
 4. The catheterassembly of claim 3, wherein the pressure sensor comprises a fiber opticsensor.
 5. The catheter assembly of claim 4, wherein the fiber opticsensor comprises an elongate optical fiber and a sensor tip coupled to adistal end of the elongate optical fiber, the catheter body configuredto receive the elongate optical fiber from outside a patient to alocation near the proximal port or the distal port to provide opticalcommunication between the sensor tip and a processing unit.
 6. Thecatheter assembly of claim 1, wherein the sensor assembly furthercomprises a sensor tip at a distal end of the elongate connector.
 7. Thecatheter assembly of claim 6, wherein the cannula comprises a tubularportion coupled to the distal portion of the catheter body, and whereinthe tubular portion is configured to receive the elongate connectoralong an inner wall of the tubular portion.
 8. The catheter assembly ofclaim 1, wherein the sensor assembly comprises the distal sensordisposed near the distal port, the distal sensor comprising an elongateconnector extending from a proximal portion of the catheter assembly anda sensor tip disposed at a distal end of the elongate connector.
 9. Thecatheter assembly of claim 8, wherein the distal sensor is disposed onor within an outer wall of the cannula and the elongate connectorextends about a circumference of the cannula.
 10. The catheter assemblyof claim 8, further comprising a protective lumen coupled to a wall ofthe cannula, wherein the distal sensor is configured to pass through theprotective lumen to position the sensor tip near the distal port. 11.The catheter assembly of claim 8, further comprising a central lumendisposed in the cannula, the distal sensor configured to pass throughthe central lumen to position the sensor tip near a sensing zone formedthrough the central lumen.
 12. The catheter assembly of claim 11,further comprising an impeller disposed in the cannula and a tip memberat a distal end of the cannula, wherein the central lumen passes betweenthe impeller and the tip member.
 13. A catheter assembly comprising: acatheter body; a cannula coupled to a distal portion of the catheterassembly, the cannula having a proximal port to enable a flow of bloodthrough the cannula and exiting the proximal port; an impeller disposedin the cannula distal the proximal port and configured to generate theflow of blood through the cannula; a sensor assembly comprising anelongate connector and a sensor to be disposed near the proximal port,the catheter body configured to receive the elongate connector through asensor lumen from outside a patient to a location near the proximalport; a bearing housing disposed within the cannula, the bearing housingcomprising a trough sized and shaped to receive the elongate connectorbetween the bearing housing and the cannula; and a processing unitprogrammed to process a signal generated by the sensor, the processingunit configured to execute a computer-readable set of rules to evaluatethe signal to determine a position of the cannula relative to a cardiacvalve of a patient during a treatment procedure.
 14. The catheterassembly of claim 13, wherein the computer-readable set of rulesevaluates the signal based at least in part on a rate of change ofpressure or flow rate over time.
 15. The catheter assembly of claim 14,wherein the processing unit comprises a look-up table (LUT) comprisingan array of values corresponding to pressure, flow rate, rate of changeof pressure, or rate of change of flow rate.
 16. The catheter assemblyof claim 13, wherein the computer-readable set of rules evaluates thesignal based at least in part on a recognition of a pattern in awaveform of the signal.
 17. The catheter assembly of claim 13, whereinthe sensor comprises a pressure sensor, and wherein the signal isrelated to a pressure of a fluid flowing through the proximal port. 18.The catheter assembly of claim 17, wherein the pressure sensor comprisesa fiber optic sensor.
 19. The catheter assembly of claim 18, wherein thefiber optic sensor comprises an elongate optical fiber and a sensor tipcoupled to a distal end of the elongate fiber, the catheter configuredto receive the elongate optical fiber from outside a patient to alocation near the proximal port to provide optical communication betweenthe sensor tip and the processing unit.
 20. The catheter assembly ofclaim 17, wherein the computer-readable set of rules includes a baselinerule for determining a baseline pressure signature from the signal,wherein the baseline pressure signal indicates proper placement of thecannula relative to the cardiac valve.
 21. The catheter assembly ofclaim 20, wherein the baseline pressure signature indicates that theproximal port of the cannula is disposed proximal the cardiac valve. 22.The catheter assembly of claim 21, the assembly further comprising adistal sensor near a distal port of the cannula, wherein thecomputer-readable set of rules includes a baseline rule for determininga distal baseline pressure signature from a distal signal received fromthe distal sensor, wherein the distal baseline pressure signatureindicates that the distal port of the cannula is disposed distal thecardiac valve.
 23. The catheter assembly of claim 22, wherein thecomputer-readable set of rules includes a rule for determining whetherthe distal port is in close proximity to or overlying the cardiac valve.24. The catheter assembly of claim 20, wherein the computer-readable setof rules includes a disturbance rule for determining a disturbancepressure signature from the pressure signal, wherein the disturbancepressure signature represents improper placement of the cannula relativeto the cardiac valve.
 25. The catheter assembly of claim 24, wherein thedisturbance rule comprises a rule for determining a difference between amean baseline pressure of a baseline pressure signature and a meandisturbance pressure of a disturbance pressure signature.
 26. Thecatheter assembly of claim 24, wherein the disturbance rule comprises arule for determining whether the proximal port is in close proximity toor overlying the cardiac valve.